4020dt

You probably have a BLD 250 or 269 also used in LR&S series 170 and 180's later engines were 282 and 308 in mid 1950's models , any of those engines will bolt up but I don't think Red Diamond series will work they are much larger etc . Years back I had a L-170 that originally had a 269 changed to a 282 it threw a rod on me and I replaced it with a 308 short block same head etc . 308 had a 2 barrel carb though I found a manifold at a salvage yard but the original one would work I just wanted the 2 barrel . There were 282 and 308's used up into the 60's in the A & B 170 and 180 series some were used in the Loadstar 1700 & 1800's

Same thing happened to my 97 few years back it was that sensor on top of filters did same as yours showed pressure on gauge but would shut down .