Do you think the 3-53 would just be slow (and how slow?) or would it have a hard time taking off with all the weight?A 3-53 in that heavy of vehicle will not be very useful. 4-53T would be better. Same transmissions, 5 speed min. I have a 10 speed in mine. I’cooler, beef up front springs, etc. Cruise at about 1750 RPM, so gear it appropriately. 4-53T takes up about same room as 6bt Cummins.
Ed in CO
The engine i have in it right now is a 454 (wich i assume is the stock engine) but it doesn’t run and we want it as a spare for our irrigation rig, we have the 3-53 sitting in a shed, it runs good and we don’t use it. I don’t expect it to go 85mph down interstate, the most it would ever go is 60mph for about a 30mile trip. Lol it’ll be a project to show off to my buddies basically.Thomas-------One of the key points I was taught in the '70s as I became a sales rep for Detroit Diesel was to compare engine torque . A 3-53 has around 205 lb.ft. at about 16-1700 RPM. The point here is most people would never be satisfied if the torque was lower than original .engine . Not knowing what engine you are replacing, the 3-53 could match or exceed the old 235' Chevy or 239" Ford flathead , but a 300" Ford 6 cylinder has 265 lb ft, the 370 Ford V-8 also at 265 lb ft., but the 429 Ford V-8 had 326 lb ft , and 460 Ford V-8 had 390 Lb Ft. I copied these ratings from a multipage brochure from a company called Powermark, that was promoting the Cummins RECON engines and POWERMARK conversion kits . I don't think you'd want to drive your truck ...............unless you considered a 4-53 with 282 lb ft .