Even amongst AMCers there's a lot of rumor and fear about the driveshaft system on these early Americans, known as the "big nut" axle. "Modern" American cars have the rear U-joint yoke fixed to the rear axle pinion shaft; the big-nut rears instead have a splined slip joint with a compression sleeve tightened with a ... big nut, tightened to 300 foot-pounds. With big wrenches.
I was warned of the horrors of working on this thing, but it simply wasn't that bad. I bought a pair of 1-3/4" combo wrenches, Fuller brand, total cost for two including shipping: $50.
It did require different procedures but none of them were particularly difficult.
Since apparantly few people have seen these things I took some photos of the procedure to debunk the mystery.
This is the rear yoke, slip-joint coupler and the eponymous big nut, cleaned for inspection.
Ready to install.
This is the pinion end of the rear axle. I took these photos to later identify the seal, which are apparantly no longer available. It doesn't look like rocket science to adapt something to though.