Originally Posted by yellowxj
Pretty sure its a 14 bolt rear. Theres a newer single rear wheel cutaway at the salvage yard with 3.21's i think. Pretty sure i just would have to swap hubs and brakes. Just not sure if the work is worth it. 2500 rpm @55 with 4.10 2300 rpm @ 55 with 3.73 or 2000rpm with 3.21
The big question is, pushing my box along the road at 55. Would the fuel economy change be noticable? Feeling like it might be. With 3.21's i could pull it to second gear and turn 2700 rpms at 55 for steeper hills?
Jeep, bus, repeat.
Before you take the time and $$$ to do any swaps I would install a manifold vacuum gauge. With the vacuum gauge you can determine how hard the engine is working.
If you are pulling above 12" @ 2500 RPM's then you should be able to step down a gear set or two. But if you are only pulling 10" I doubt you would be able to run gears any faster and see an improvement in anything. In fact, you might actually end up using more fuel in order to do the same work.