RudeXJ

I live outside the US so aftermarket parts are expensive and tricky to find, and XJ's are scarce in junkyards and in general.

I got a 3 inch lift and a new set of 31's on my 00 4.0 AW4 XJ (dana 35 and 30 axles with 3.55 ratio) and I've noticed a massive dump in power. We got lots of mountains here and dying while climbing hills gets real boring, plus it sucks on the trail.

I don't plan on going any taller or bigger tires, just want to make this setup awesome.
Currently looking at re-gearing and my options are these: pick up a set of 4.10's from the US $$$ or swap axles with a guy locally who has a set of 3.73 axles (also 30 and 35) for about half the price it would cost to install 4.10's. Axles come from a 2.5 turbo diesel, couple those around here.

My question is: How do 3.73's compare to 4.10's with 31's, cost and opinions on the future mods aside. In my understanding 3.73's are slightly under geared and 4.10's over geared for 31's. I'm kind of answering my own questions here, but I'm looking for people who run these setups to share experience.

Any idea what rpm I'll be running at 60mph?

Thanks!

4.3L XJ

If you want to hit it on the money, 4.10s are it for 31s. If you want to swap out axles, look for some out of a 4 cyl gas, if available. They have 4.10s

RudeXJ

4 cyl XJ's are rare as hens teeth round these parts. I thought the technically perfect ratio for 31's is 3.92...

5-Speed

I run 3.73s with 31s and love it BUT I have a manual trans. 4.10s with an auto trans would be nearly identical to what I have.

Another vote for 4.10s here.

RudeXJ

I hear ya, yeah with 3.55's the AW4 shifting at way too low rpm, having just put these 31's on I can physically feel I have to step on the skinny pedal much harder to get the same power output...not cool.

srb53150

3.73 wont show you much improvement, go w/ the 4.10

00jeepXJ

100% this. If you have an auto you will want to do the 4.10's so that you have the power and pep back. With the manual trans it's the 3.73's.

00t444e

You can manually keep the transmission in a lower gear and shift when you want it to, I do that all the time, I have 3.55s with 31s and it does just fine, I have even towed a car on trailer with it.