I have recently posted asking about gears/posi and whatnot. I have decided to go at least 3.55 rearend. The truck is an 88, f150, shortbox reg cab, 4.9, 4x4, m5od. I want to do a 2" lift/level and put 31" tires under it. I don't tow, but what would be better and why? 3.55 or 3.73?

 

What gear ratios do you have now? Most of these trucks came with 3.55s. When i had my auto 94 i was happy with my 4.10s on 31s, but when i bumped up the tire size to 33s i caught myself wishing for some 4.56s.

 

Almost all of the trucks I've seen with the 4.9/m5od combo had 2.73 or 3.08 gears. The 302/351/aod/e40d/c6 often times had 3.08 (c6) or 3.55(auto with OD).

 

3.08 currently

 

My '88 came with the 4.9, 4x4, M5OD and 3.55 gears and they work well. It's on 31's at the moment. I can't see 3.73 gears making the truck any better. Only thing I'd rather have is the ZF-5 transmission to have the granny 1st and reverse.

 

You would want the 3:73 with 31s

 

My 94 F150 4x4 5 speed short bed reg cab has 3.08's and ain't bad with stock tires.

And my 89 F150 2wd C6, has 2.73 and again on stock tires, it cruises nice right on 2000RPM @ 55mph.


A friend of mine has a 2wd 5 speed 94 F150 straight 6 with 31" tires on it and 3.08's, it's abit sluggish off the line, but does fine otherwise.