Lengthening a driveshaft (by adding a short length of tube to the existing tube) is not recommended. Find a longer one and get it shortened. :thumbsup: I would hang on to your current one for the day you upgrade to a Dana 44. :D
In my humble opinion, the AMC 20 is quite under-rated. It's gotten a bad wrap from the CJ 2-piece shafts, and the ginormous weight of the Waggys (5k+ with passengers) sitting on them. The MJ has neither of those drawbacks. :D
You only need the factory parts off a PS equipped MJ/XJ with the same engine. Pump, resevoir, brackets, belt, power steering box, etc. Anything associated with it. :thumbsup:
Where do you live?
You can snag an AX-5 from a 2.5L/2.8L Cherokee/Comanche or 2.5L Wrangler of any year.
Another good upgrade for you is to grab the rear axle out of that rig you get the trans from. As a general rule of thumb:
2.5L+4spd manual = 3.55 gears,
2.5L+5spd manual = 4.10 gears
Chrysler's new oil spec now call for 10w-40 engine oil in the AX-15.
And for what it's worth, I've had a couple manual trannys in my Jeeps that needed to warm up a bit to work well. :dunno:
Once the XJ is on the dolly, I would unbolt the rear shaft from the rear axle (it's only 4 nuts) and strap it up securely under the Jeep. If you pull the driveshaft from the t-case, the fluid will come pouring out. :thumbsup: