gearing... any guesses?

I bought a 2001 xj off a friend of mine when he grenaded the rear end. It's auto, has the full time FWD option (np242) and anti-lock brakes. (4.0 engine, sport, 4 door) From what I've read thus far, and the FSM seems to confirm, the only axle offered with ABS is the dana 35. That sound right to people?
Abridged version- I've replaced the rear end and guessed on the gears (I know). Had some bearing issues and fixed them. Now I seem to have a bad pinion or carrier bearing. The rear end I put in had ABS and 3.55 gears. Thinking I might just get another rear end until I went to verify the front end gearing- no tabs, cant make out any housing markings.
How far could you drive miss-matched axles before they destroyed themselves? I thought that might happen kinda quick. I've gone about 75mi.
I can get another rear end but I've gotta let my guy know the gearing. It dosen't have the tow package.
Thoughts?

Yeah, live and learn but I'm trying to make the best out of what I have to deal with.
Cheers,
Buddy

Autos are 3:55, standards are 3:07

It should be a Dana 35. Gears should be 3.55 for both the front Dana 30 and the rear Dana 35 unless your buddy regeared. Mismatched ratios shouldn't destroy the axles, they would probably take out the transfer case first. Why not just pull the front diff cover and count the teeth on the ring and pinion to be sure? It might also be marked on the ring gear as "41/9" or something like that.

it will be fine to drive unless you put it in 4wd. If yo uput it in full time 4wd it would probably drive, but you'll spin the diff in the t-case at a tremendous RPM and kill it. Part time mode would be terribly ugly.

what weirdo said is what you need to do, take the D30 cover off and count the teeth, or look for the ratio stamped on the edge of the ring gear.

If your axles had mismatched gears you wouldn't get very far in 4x4, it would be acting like you had brakes locking up.

the_weirdo said:

Why not just pull the front diff cover and count the teeth on the ring and pinion to be sure? It might also be marked on the ring gear as "41/9" or something like that.

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I would but I'm in NC and the Jeep is in NY and pops isn't good with that stuff any more. I thought running miss matched ratios would take out the weakest link in the drive train, be it the transfer case or the weaker differential.
My buddy isnt too good with the wrenches so I'm not worried bout a regear.
Sounds like its 3.55 but I forgot about the ring gear. Maybe I can get him to check it.

just pull the front DS and you won't have issues, unless you want 4wd

o-gauge-steamer said:

Autos are 3:55, standards are 3:07

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3.73 with an automatic was also an available option in '01. No idea if a deeper axle gear was available for the manual transmissions, though.

joe_peters said:

If your axles had mismatched gears you wouldn't get very far in 4x4, it would be acting like you had brakes locking up.

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this is what I thought, so I may have guessed correctly...