will the gear box from a 9? cherokee bolt up in place of a 79 cj one? i can't get the pitman arm off of my stock one to put the xj one on, i've tired pb blaster for 6 days, 2-jaw puller, pitman arm puller, heat, and bfh (big fawkin hammer), still won't budge

The fittings will be different your CJ uses flare style the XJ has o-rings, no biggie if you take it to a hydraulic shop to swap the fitting, only need to mess with the high pressure line. If you can't get the pitman arm off yourself then take it to a shop.

the steering input shaft splines may also be different. But can also be solved.

any definate on the splines?, cause there are 2 at the boneyard i can go get, or just pay the $130 for a reman w/ lifetime warranty

Believe there are only two different size shafts and CJ's use a bell coupler at the box. If you need the bell coupler for the smaller shaft then use one for manual steering, you can get them at 4wd hardware.