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vtfireman85

Auto- manual swap

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Wondering if anyone has swapped out an auto in a medium duty truck? Long saga but still looking at a C70 with 3208 cat and an unspecified Allison. The truck is extra clean and desireable in many ways but I’m wondering what the possibilities are of swapping an Eaton.. say 9 speed, into this truck. Apart from the obvious lack of a clutch pedal and master cylinder, drive shaft adaptation and the like what would I need to be looking for and what would be the best candidate? I assume I’d need a flywheel? Can one just be attached or is it balanced with the crank in a 3208? Are bell housings somewhat generic in these trucks? What about speedo?

any insight would be appreciated 

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SAE bell housing, I believe but you really need a donor truck's entire system.

Is the Allison not working?

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2 hours ago, New Englander said:

SAE bell housing, I believe but you really need a donor truck's entire system.

Is the Allison not working?

No it’s fine, it’s just s big unknown. And it’s a big blemish on the trucks desirability, are you saying it’s a standard bell housing? I believe it’s an Eaton behind our 427 but I assume that would be different? That’s a 76’ the new truck is a 90

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Popular transmission for that time was a 6613 behind that 3208. In the early to mid 80s. It is a lighter version of the super big 13 speeds and this one isn't light by any means. They were used behind ih, dt466, 3208s and even 427 Chevys. You should be able to find a 3208 flywheel in a wrecking yard and clutch pedal can be swapped from donor truck. There are other trans even a bigger 9 or 13 speed will fit but the 6613 will give you deep reduction in the low side then a regular nine speed after that. Just no overdrive. The 66 means 600 lbs input torque and I think they made just a 613. You could always find a newer manual trans they had those 6+1 in newer trucks but never been around them.

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Here are pictures out of a 82 chevy sales lit for dealers what could be available. The first basic gas 5 speed, the second more heavy duty, the last pictures are the big roadrangers. Some of them were for behind the n14 or DD but the 6613 is like the last picture just a junior size.

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Measure the distance between bolt holes on the bellhousing and I could tell you what size it is. It  would be an sae standard. As for clutching you could build brackets and keep it mechanical or use a hydraulic system. 

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6 hours ago, vtfireman85 said:

No it’s fine, it’s just s big unknown. And it’s a big blemish on the trucks desirability, are you saying it’s a standard bell housing? I believe it’s an Eaton behind our 427 but I assume that would be different? That’s a 76’ the new truck is a 90

You can always do the swap and yes, standard SAE housing identified by bolt spacing/circle. If there's nothing wrong with it just drive it. I've never heard that they're unreliable.

My friend has two International dumps, one manual and one auto, what model I don't know but I do know that he's not unhappy with the auto.

I have an Allison in a yard truck. It never gets out of first and reverse but if it was a road truck I wouldn't bother to replace it unless it broke and was not economically feasible to repair it.

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I run  allison 653 along with 3060 series. Great transmissions in the field for loading crops when going slow is the norm. Dropping  the 653 transmission into 1 from a fast speed or pulling a full load and dropping into first will possibly grenade  the case, Don’t let that part scare you off . You might have a 654 which doesn’t have the low gear. Just priced out a rebuilt 653 2 year Unlimited miles was $2,700 plus R R.  Putting a stick in isn’t cheap with clutch and P plate and the drive line will need to be changed out. Never had one that was correct length when changing to automatic

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Thank you all for these responses, and pictures. The Allison, as it turns out, is an MT643, and while it’s not my first choice by any stretch, it is a heavy duty thing. I think it’s rated at 73k and 250 input HP, so I suspect itl handle a 29k truck. Seems very well behaved, slow to respond but utterly consistent. Like most fire trucks I’ve ever driven,  everything in this truck feels “new”. Even though it’s nearly 30 years old.

i think we’re going to run the Allison, we were worried it was a 540 series and that might have been a deal breaker.

on the department we have a 78 ford  COE with what I’ve been told is a 3208 painted blue and branded ford in front of a 540 Allison, it’s slow and sluggish and slushy feeling, like maybe there is apple sauce inside it. But it always gets there, has decent pose if you just push the pedal to the floor and hold it there, mercilessly, it’s old and ugly and it will pump water better than any newer truck on the department.

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