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K10/K20/K30 Manual transmission swap


Adam - NC
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I've loved square body Chevys since I was a kid.  My first vehicle was a '76 long bed 2wd with a 250 cubic inch in-line 6 and a 3-on-the-tree manual transmission.  I could have gotten into a lot more trouble with a 350 and 4x4....

If I were to find one with the 4 speed manual and 4x4, is there a later 5 speed manual that would swap in easily?  Or a later transmission and transfer case that would be an easy swap? How hard is it to swap from an automatic to a manual if I find a deal I can't refuse?

 

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Really depends on the money you want to spend..quite a few options out there. 

Myself id stick to what can be mounted to a np205 without an expensive adapter.

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Maybe an nv4500....id have to do a bit of searching tonght..

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What gears are in your diffs?

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As pretty much everything but a photo copier has been bolted to a 350 small block, and a 350 small block is the same pattern as a 4.3,305,327, etc etc I would say that the sky is the limit, personally I would be doing some research to see what was used in the 88/89/90/91 model years with the crossover body styles and go from there, I think you will find the best interchangeability there. 

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Steer clear of the 5-speeds from the 88-90, I think. Dad had the 88 1/2 ton 4x4 with the 5-speed. It was a problem child and the parts supply was bought up in the early to mid 90’s. It was the same transmission as used in the S-10’s and I believe Ford rangers.

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3 minutes ago, jeeper61 said:

I always thought a square body with a 8.1 and a Alison would be nice.

I like an auto for wheeling, no lost momentum in the soft stuff. 

 

A 5.9 with an Allison in a square body!! The Cummins will fit with the use of a shoe horn. A friend of mine put one in an 86 with the 4 speed behind it , with 373’s front and back. 

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35 minutes ago, jeeper61 said:

I always thought a square body with a 8.1 and a Alison would be nice.

I like an auto for wheeling, no lost momentum in the soft stuff. 

 

I have an 8.1/Alison 5 spd.  They have 275000 or 276000 on them and have never been apart. Now saying this it seems like support for the 8.1 isn't great.  The drive by wire gas pedal, nla throttle body, and engine limp mode are annoying to say the least.  They are a great combo but the electronics kill me. 

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6 hours ago, Adam - NC said:

I've loved square body Chevys since I was a kid.  My first vehicle was a '76 long bed 2wd with a 250 cubic inch in-line 6 and a 3-on-the-tree manual transmission.  I could have gotten into a lot more trouble with a 350 and 4x4....

If I were to find one with the 4 speed manual and 4x4, is there a later 5 speed manual that would swap in easily?  Or a later transmission and transfer case that would be an easy swap? How hard is it to swap from an automatic to a manual if I find a deal I can't refuse?

 

From what I remember, it has been a bit. A nv4500 will fit in with a adapter. The medium duty 5 speed in the 1/2 ton light 3/4 is crap don’t use it.  For big money you can get the newer trans adapters also. 20 years ago I used to fix Chevy np435 4 speed, Eaton truck trans ,IHC , Clark transmissions I could tell you exactly what was needed but my Alzheimer’s is kicking in.

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1 hour ago, hobbyfarm said:

I have an 8.1/Alison 5 spd.  They have 275000 or 276000 on them and have never been apart. Now saying this it seems like support for the 8.1 isn't great.  The drive by wire gas pedal, nla throttle body, and engine limp mode are annoying to say the least.  They are a great combo but the electronics kill me. 

Yup that is the problem you'd have to use a cable throttle body and custom tune to get around that 

Would be be easier to go LS motor but I don't think the Alison fits them. 

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I gotta ask why the 208? Or any chain drive transfer case for that matter?

I guess it comes down to purpose i suppose. I choose heavy duty. Np435 to 205 to 60/70. I have a 75 1 ton dodge and thats what i run. The 435 doesn't really allow for 80 on the hwy but it will do it. The truck had a 445 before 435 and i will say the 445 has a better spread of gears but as far as i know will only mate to a 203. The 203 was toast when i got the truck and im not suprised. 

Tell us a little about your wants, needs and reasoning. Then we will give you 20 more opinions. Lol

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The 208 is a great case they didn’t have the chain stretching problem the 203 had and a ton lighter and what are all modern trucks using now?chains? Seen a lot of 208 in pulling trucks with good success. But that my 2 cents and I’m sure there has been someone who broke one, but I broke a 205 before to. 

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if it was me a nv4500 and a adaptor to run a np205 that way you can still run your front axel and i've always had the best luck with them plus I still got a couple laying around you'll have to get a hydro boost system if you don't already have one, either aftermarket or factory, last i looked the factory ones where going for some stupid prices but thats been awhile

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11 hours ago, Alan Dinan said:

Steer clear of the 5-speeds from the 88-90, I think.

Oh wait, Dad's 89 and my 88 both had 4-speeds... It was my 97 half ton that had a 5 speed. Shortly after I bought it, it popped out of gear VIOLENTLY, and after that it always had a slight clash going into any gear. Took it back to the dealer and told them what happened, "could not reproduce customer concern." That truck was a POS from the beginning, yet I still drive Chevys.

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7 minutes ago, Matt Kirsch said:

Oh wait, Dad's 89 and my 88 both had 4-speeds... It was my 97 half ton that had a 5 speed. Shortly after I bought it, it popped out of gear VIOLENTLY, and after that it always had a slight clash going into any gear. Took it back to the dealer and told them what happened, "could not reproduce customer concern." That truck was a POS from the beginning, yet I still drive Chevys.

Your supposed to push the clutch in to shift😂.

actually i had 240+k on a 97 half ton, while I certainly wouldn’t recommend that trans for big engine or heavy truck i had absolutely 0 trouble with it, it was about the most forgiving transmission I've ever driven. The 4.3 lacked a little in the giddyup  department but it was really a decent little engine. 
my personal dream truck is a 93 K1500 with a 350 /5 speed extended cab.

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One thing to say those old transmissions were good but not trouble free either and transfer cases has trouble. The aluminum body 208 transfer case you could crack the housing if u joints were bad or got stupid spinning with them. The old 205 were tough but you could have chain problems running gear oil they were recommended for engine oil. The old gear driven think it was a 203 were very good but used to have to put bearings in them also. Even the nv 4500 trans you would find a cracked housing on them leaking oil from top bolt holes. The old 435 trans were good but synchro and bearing issues and in the heavy duty application,  c50 trucks and such there was a upgrade to put spacers or change the on countershaft. They would let gears move a bit and walk the top synchronizes into neutral. Between my truck sales buddy and just the popularity of Chevy gmc grain trucks around here we used to rebuild those trans really often. Then a lot of nv 4500s around the country they needed work more than the old ones.

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7 minutes ago, vtfireman85 said:

Your supposed to push the clutch in to shift😂.

actually i had 240+k on a 97 half ton, while I certainly wouldn’t recommend that trans for big engine or heavy truck i had absolutely 0 trouble with it, it was about the most forgiving transmission I've ever driven. The 4.3 lacked a little in the giddyup  department but it was really a decent little engine. 
my personal dream truck is a 93 K1500 with a 350 /5 speed extended cab.

We had guys that pulled trailers and stuff with them. They lasted better on just light duty driving than the heavy duty transmissions. From what I remember you could not disassemble them without special equipment.

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13 minutes ago, vtfireman85 said:

actually i had 240+k on a 97 half ton, while I certainly wouldn’t recommend that trans for big engine or heavy truck i had absolutely 0 trouble with it, it was about the most forgiving transmission I've ever driven. The 4.3 lacked a little in the giddyup  department but it was really a decent little engine. 

Ya dun went and got me started on that POS 4.3 engine. It was nothing but check engine lights and roadside assistance from the get-go. It always had a "buck" during acceleration from day one. Multiple dealers, "Could not reproduce customer concern." I guess if you drove it like a Detroit, it didn't do it, but if you accelerated like a human being, it would buck.

They would only do something if it threw a check engine light. Then it was usually plug wires, cap and rotor. It would run well for about 5 minutes out of the dealer lot then buck-buck-buck... I finally took it to an independent mechanic. They agreed something was wrong, spent DAYS, and could not find a problem. Everything tested in spec, yet it ran like crap. Finally they called, "GET THAT POS OUT OF HERE AND DON'T BRING IT BACK. No charge."

Left me on the side of the road a sum total of 3 times. Two ignition coil failures. Then finally the real problem, what had been wrong right along, all 96000 miles I drove it, came to light. I was at the farm helping Dad, and it would not start when I went to go home. Dad took it to a mechanic out there, and he found three fuel injectors that were not firing at all, and the other three were misfiring frequently. I'm sure that was the problem from the get-go. I had him get it running, and traded it for a brand new 2003 Chevy with an automatic and a V8. That truck was flawless, I drove it over 12 years and 218000 miles.

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10 minutes ago, Matt Kirsch said:

Ya dun went and got me started on that POS 4.3 engine. It was nothing but check engine lights and roadside assistance from the get-go. It always had a "buck" during acceleration from day one. Multiple dealers, "Could not reproduce customer concern." I guess if you drove it like a Detroit, it didn't do it, but if you accelerated like a human being, it would buck.

They would only do something if it threw a check engine light. Then it was usually plug wires, cap and rotor. It would run well for about 5 minutes out of the dealer lot then buck-buck-buck... I finally took it to an independent mechanic. They agreed something was wrong, spent DAYS, and could not find a problem. Everything tested in spec, yet it ran like crap. Finally they called, "GET THAT POS OUT OF HERE AND DON'T BRING IT BACK. No charge."

Left me on the side of the road a sum total of 3 times. Two ignition coil failures. Then finally the real problem, what had been wrong right along, all 96000 miles I drove it, came to light. I was at the farm helping Dad, and it would not start when I went to go home. Dad took it to a mechanic out there, and he found three fuel injectors that were not firing at all, and the other three were misfiring frequently. I'm sure that was the problem from the get-go. I had him get it running, and traded it for a brand new 2003 Chevy with an automatic and a V8. That truck was flawless, I drove it over 12 years and 218000 miles.

I did have issues with electronics, did 6-8 fuel pumps, of various brands until finally i had to put a clutch in in the process I found the fuel line up over the back of the block was kinked in a factory bend, that seemed to clear up the fuel pump issue, the latest one went from 170k-240+ when i finally retired it. Seems like i went round and round with cam sensors and distributor caps too. Maybe I just needed a decent mechanic instead of a Haynes manual and a 16-24 year old ameture mechanic (me) 

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13 minutes ago, dale560 said:

One thing to say those old transmissions were good but not trouble free either and transfer cases has trouble. The aluminum body 208 transfer case you could crack the housing if u joints were bad or got stupid spinning with them. The old 205 were tough but you could have chain problems running gear oil they were recommended for engine oil. The old gear driven think it was a 203 were very good but used to have to put bearings in them also. Even the nv 4500 trans you would find a cracked housing on them leaking oil from top bolt holes. The old 435 trans were good but synchro and bearing issues and in the heavy duty application,  c50 trucks and such there was a upgrade to put spacers or change the on countershaft. They would let gears move a bit and walk the top synchronizes into neutral. Between my truck sales buddy and just the popularity of Chevy gmc grain trucks around here we used to rebuild those trans really often. Then a lot of nv 4500s around the country they needed work more than the old ones.

205 is gear 203 was chain the 4500's did lack when stock but one thing about them is they used them in the second gen cummins trucks not the exact same but you can get custom parts for them now to make it a lot better trans

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I had a 91 Chevy extended cab four-wheel-drive 4.3 with a five speed junk aluminum transmission. I bought it with 30,000 miles drove it to 150,000 miles then sold to my neighbor who ran it to 250,000 miles and neither of us had a problem with the tranny or engine. It all comes down to how it came down the assembly line and then nut behind the wheel. And I had an S 10 with a 4.3 that had well over 200,000 miles on it never had an issue with it. 

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