3.38 rear end? I understand why you are having trouble with lugging under many situations which you mentioned.
Weren't the original rears 3.90?
The engineers did that for a reason. Napco trucks are heavy, I would guess that the suburbans are even heavier. In order to move that much weight out of its own way with a 235, you need 3.90 gears.
You mention "big tires". How tall? Taller than stock will add to your problems, compared to stock height.
I do not believe that any cam will make your 3.38 geared truck, with a 4 speed do what you want.
Carl
Last edited by 52Carl; 08/17/2019 11:21 PM.
