I found a Dana 70 rear axle from a ford 1979 F350. I want to put it in my 1999 xj. The spring pads are at the correct distance to line up, but what about the U-joint yokes, what else will have to be done?

I think you're going to be disappointed with all that unsprung weight. What tires are you planning on running?

That being said, I don't think the u-joint yoke is going to be your biggest problem. You can always have a new yoke welded onto your driveshaft that will match the yoke on the axle. You may have to shorten the driveshaft anyway, so that could be done at the same time.

I'm surprised that the spring pads on the D70 axle line up correctly with the springs on your XJ. Assuming they do, how does the overall width of the axle compare to the width of the OEM axle? I'm assuming that the D70 is a full floating axle, as most one-ton axle are. If you have to shorten the axle, then shortening the axle housing will be the least concern, cost-wise. Getting shorter axle shafts in the housing will be a higher expense.

Also, don't forget that the bolt pattern of the new axle will undoubtedly be different than the bolt pattern of the OEM axle. That means you'll have to buy new wheels (and probably tires) that will fit the new axle's bolt pattern (and get them with the correct ofset, which may involve getting expensive custom wheels). And, after doing that, you'll have different wheels on he rear of the vehicle compared to the front, which means that ou'll have to elect which type of spare tire to carry, because the spare will only fit one of the axles. That consideration alone would make me look at the possibiloity of changing out the front axle, too.

Boat anchor. Just because it's free doesn't make it a good option....

Here !! Here !!

right...i didnt even consider the bolt pattern. Ok well thanks for talkin me out of biting off more than i could chew, and btw its not free, He was asking $200 obo for it, but he never responded to my email anyways.

I think you're making a wise decision by rejecting that D70. An axle like that might be best suited for someone who is looking to upgrade the axles on their 1/2-ton or 3/4-ton full size pickup, and then only if the front axle is swapped out, also.

I had a 1-ton Dodge W350 with a front D60 0and a rear D70. That thing was heavy!!! Since it's a full-floater, the rear brake drum also has the hub into which the wheel bearings are fitted, etc. Did I mention that the rear brake drums on a D70 cost about $175 -- EACH?