With 33s, 3.55 will take you back to stock:

33/28.5 = new ratio/3.07

(33/28.5)*3.07 = new ratio = 3.55

 

It really depends on what you value more and what's easier to find...

3.55:1 really close to stock, ridiculously simple to find and cheap
3.73:1 deeper which is better as you have a lot more rotating mass than stock, found in pretty much Renix XJs or in TJ axles (which may be LP D30), in either a D44 or D35
4.10:1 not as rare as 3.73:1, worse highway performance but better off road

 

Damnit gearing has got to be the hardest most opinionated decision for xjs haha. I may revamp the plan to pull 410 or 373 front the junkyard and just clean em up and throw em in and if it's not enough I can just regear my original axles on the side
I want a little more than stock but if a little more than stock is too hard to find without wasting money I think ill just pull some 3:55 and see how happy I am

 

For 3.55:1 just grab whole axles dude. No point in spending all the money and time on gears.

Also you are probably not going to find 3.73:1 gears for an 8.25 unless you go looking at KJs. Not sure if the gears are 100% identical

 

yea I'm gunna grab full axles this weekend... No need to buy gears now that I realized I wasn't accounting for the final drive ratio and all... I happened to notice A LOT of the threads I started reading on gear ratios with AX 15 topics... Well they ended up being about aw4 because ppl just chime in because they don't read the whole thread and just assume everyone has automatics hahaha so I was getting confused but now that you all helped and stayed on the topic of ax15 I got it in my head so thank you all! Haha

 

Yep I have 3.55:1 on 31s with a 5-speed and love it.

Cheers

 

Kj and xj 8.25 are identical, it's the later ones(compass/patriot I think) that made the 8.25 in to a full floating design. Gears should still be the same

 

No idea about floatiness. Dakota 8.25s have some width and lug pattern differences too. The KJ diffs I've been into have an ABS tone ring, I can't remember if this is part of the ring gear, the diff carrier, or inserted or what.

Seems worth a look though. Those junkers with the 3.7L V6 seem to all be 3.73:1 - if you want to regear the back!

And on that note, 3.73:1 HP D30 gears can be pinched from any older XJs, and you should be able to find them in YJs and TJs with that horrible 3-speed junk.