Alright guys, since this is a much friendlier forum, I figured I'd ask here.
I am rebuilding my 1983 CJ7. It has a 5.0L Ford V8, A T177 Jeep 4spd tranny mated to a Dana 300. It will also have a 14bolt rear end and a Dana 60 front. I'd like to run 40" tires.
I've been looking at 5.38 gears, but don't know if those will be too deep.
Check out the grimmjeeper gear ratio calculator. Just google it. it will allow you to compare different gear sets with drivetrain/tire combos. I use it all the time. awesome tool.
T-17X series trans are solid transmissions but in my opinion are geared a little tall & making a differential gear change more desirable. That's why I ditched my T-176 and adapted in the Ford NP435 (wide ratio) to the D300. In doing so, I was able to run tall gears for the highway and have plenty of bottom end for the trails... 71:1. Pretty good for no doubler or 4:1 kit and just some stock junkyard **** I rebuilt and bolted together. This was with 4.10's and 37's. I was only running built Waggy D44's.
I'd think about what your end goal its. Wheeler/DD (mine was) or trailer queen that rarely sees pavement.
I loved being able to stay under 2500 RPMS and go 70mph with no issues and still have great crawling gears.
I'd be looking at 5.13's. you'll have plenty of power to push it without dogging it. You'd be hitting 3000Rpms at 70mph in 4th gear (1:1).
The 2.61:1 reduction of the D300 (stock) without a 4:1 kit would get you about a 51:1 final drive in 1st/ 4Lo.
With a 4:1 kit, your looking at a 78:1 1st gear/4Lo final drive. Pretty good bang for your buck.
4.88's are another option but are going to feel a little tall in the lower gears on the street.