From what I find the GMC motorhomes offered the 455 in 1975 and the HP is around 190 and torque is around 350. No doubt at a lower rpm than a sbc. I would have to think that your 455 would be a smooth low end powerful engine. I take you have a turbo 400 trans. It should easily handle low 3' s in a rear gear. Not as a drag truck tho.
I have a 70 442 -- yea 360 hp and 500 ft of torque and 3.55 gear --- and I did add an OD trans. It does not care, made it a real 442 -- kinda-- and really like the OD.
If your 455 runs like it is supposed to I would keep the 3.73's and invest in an OD trans.
Last edited by 42465967; 01/14/2019 4:55 PM. Reason: words
