I believe these use a non serviceable staked in u-joint. Ran into this problem years ago with several mazda pickups. Those driveshafts had to be taken to a clutch and u-joint shop and machined out for replacement joints. A bit more spendy than the average rebuild.
Cheapest option is going to be hitting the yards for a good donor I'd say.
My experience with these drive shafts is they get a "bad" spot right where they ride because they do not flex that much. Three out of three used driveshafts I owned had marginal or worse u-joints. When I had it out I put in the best of the three that I had but expect to have to replace it soon. You can drive it with bad rear u-joints with little risk, it just gets noisy when you use the 4wd.
I have not replaced a u-joint on these cars yet but the cheapest thing to do is remove the drive shaft and take it an automotive machine shop (you can even drive your Turc in 2wd to the shop). Then have them press out the old u-joint and install a new one. The last time I did that it was only about $45 including the u-joint (on a different car). It might be possible to pound or press out the old one if you have a suitable size aluminum dowel as a drift and a large vise. Though you have a large risk of damage to the shaft or yoke.