If you go to searspartsdirect.com, you can download the OM.
It has an exploded view of the transaxle that "might" be helpful.

Here is a link that might be useful: Manual

As long as your friend didn't bugger things up too much, these aren't too hard to work on, but are expensive for parts. Tractor was made for Sears by Murray.

Transaxle is a conventional Peerless 930 (930-042) with special axle shafts. Sears and others say NLA, but others offer for around $400. The U-joint (320531MA) and the Hub (12280E701MA) are each around $100. Some of the other parts are available show NLA from Sears, but others may have them.

Cheapest fix might be to find a donor tractor for parts, or convert to a conventional 930 transaxle with long axles and go to two wheel steering. Transaxle mounts to frame the same, and with new wheels on end of shaft you should be good to go.

Well, thanks to all, as i checked with my local "parts for anything" retail shop. They informed me that the parts are available! U-joint costs $98, axle shaft is: $38.
So, i called the owner, and informed him of my progress. When i told him the availability and list prices of the parts, he decided to try to fix it, first, without buying any parts!
Well, him fixing it in the first place got him to this point, so I'm going to let him "fix" it some more!
thanks to all who answered my questions, and for your advice. I'll let ya know how it all turns out.
Rusty J.

Up-date: The owner dismantled the u-joint, and it was as i suspected. Welding on the U-joint took the temper out of the joint, and that super-hard axle took out the splines in the u-joint! He'll still need an axle, and a u-joint. The parts are around $125, plus tax.
now, he wants to know if i think he could just weld the u-joint to the axle, and run it that way.
I suppose he could try it,me never having any experience with those trannys. I offered him a used 6-speed tranny that might work, or i'd just buy the tractor, for parts.
That was this afternoon, so its up in the air.
I'll keep ya informed.

Hi!
I have a 1990 Sears Craftsman II 4 wheel steer
model C950-60922-0 with the Peerless 920-027 trans-axle
with the 12hp engine. I searched every where for a parts list for the rear steering and didn't find anything. I was wondering if someone with a manual could tell me the part number for the rear axle u-joints. Info much appreciated.
Bob

Your model numbers don't match Sears "convention".
As in the first post it should be in the format-

XXX.YYYYYY as in
536.255870

Thanks for your interest. That is the model number on the decal. I think it must be a Canadian model only. Sears doesn't cross it to a similar US model and has absolutely no info on it now.Noma made a 12/40 that looks the same. Luckily I found a supplier that sells those small u-joints by size.
Thanks !
Bob

After doing some research, I have the equivalent of a Noma 12/40, model #4012-0100 code 9215. It is almost impossible to find info on this model also.

320531 is the joint for the tractor mentioned in this thread.