I did a search and found lots of discussions regarding pinion flanges, but wasn't able to find an answer to my specific questions, so here goes...

Cruiser has a '71 transfer-case (square flange) and I recently picked up a '75 rear axle which has the round, larger bolt-pattern pinion flange. I then scrounged up a large bolt-pattern driveshaft flange to mate it to my square-flange driveshaft.

However, the u-joints from my square-flange driveshaft look different from the u-joint that is on the later-style round-flange. My square-flange u-joints have a clip holding the u-joint on the outside of the ears, whereas the round-flange has the little c-clip thingies (technical term) holding the caps on the inside of the ears.

My question is: which style u-joint should I use that will safely connect the later-style round-flange to my square-flange driveshaft?

Thanks a bunch!

There are a couple easy ways of doing this.
The simplest is to swap the entire yoke from the large pattern driveshaft onto the smaller patterned shaft. the spline count on the driveshafts are the same. The smaller pattern will mate to your transfer case and the larger pattern will mate to your pinion.

The other is to offset your driveshaft flange on the round pinion flange and drill a second set of holes.

Just a heads up though... If your axle was truely ID'd as a '75 and it does have a round pinion flange, then it probably means that aftermarket ring and pinion gears have been installed. As far as I know, the round flanges were only avalilable for the later style and aftermarket fine splined pinions. Stock '75 axles came with course splined pinions and 4.10 gears. You might want to double check the gear ratio before you get everything installed.

Sorry, I wasn't clear enough. All I had was the flange part with the u-joint still in it and not the slip-joint part of the later-style yoke. I guess I still need to get the slip-joint part of the yoke to make it work. I'll call Specter for a used one...

I got the axle from Mike at Bent & Twisted. He said it's got brand new 4.10 gears in it, so I s'pose that makes sense with the round pinion flange.

Thanks again!

Honestly, I think you're headed in the wrong direction here.

71 transfer case = early pattern
75 rear shaft = later pattern
driveshaft = later pattern

IMO, mixing-matching u-joints on the driveshaft is a nightmare, but workable. You will be much happier, IMO, if you swap out the transfer case brake drum with one from a 74-later FJ40. This way, your u-joints stay the same, you run the later-larger pattern, and potentially the driveshaft could be installed either direction as well.

And yes, the brake drums from a later transfer case DO interchange with the brake drums from an earlier transfer case. Drain oil, pull the nut, swap drums, refill. :D

Actually, what I've got is:

71 transfer case = early pattern
driveshaft = early pattern
75 rear shaft = later pattern

I agree that having two different u-joints on the same d-shaft isn't the best, but until I can scrape up the change to get a completely new one from High-Angle, it'll have to do.

Hmmm... swapping the brake drum is something to think about...