rear end ratios

[1979jimmy350]

what would be the best gears to run with a 700-R4/NP203 combo. I am running 31 inch tires with stock axles on a 1979 GMC Jimmy with a 350. I am looking for some thing that gives me the best gas milage.

 

[mudhog]

3:73's to 4:10's would be good for a setup like that

 

[1979jimmy350]

I have 3.40's at this time will these be better or worse for gas milage vs. 4.11's