OK  It's happening again "the dreaded while your at it syndrome".  Was under the car looking at frame, replacing the gas tank and I noticed that there is grease that looked like it was coming from the side yoke seals on the differential.  After dropping the strut rods and spring and half shafts I think it's actually from the universal joint.  They were replaced and have grease fittings so I think Bubba pumped them full and it was spraying all over the undercarriage!  Anyway, I want to drop the differential anyway (to replace cover - see below) so I will check the seals.  A few questions:

To replace the seals, you must remove the yokes. If you are replacing the rear cover, you can get to the snap rings that hold the yokes in, and replace the seals.

If the heli-coil is installed properly, the threads in that are stronger than the cut threads in the diff anyway, so the use of a heli-coil in itself would not be a reason to replace the cover, for me.

Don't know exactly how long the bolts are for the spring mounting, but they should all be the same length, from what I can remember.

The front bolt on the diff bracket can be a little tough to get to, but you must remove the driveshaft first. That gives you more room to play with. Removing the bolts for the driveshaft can be done with a long extension and socket from the front.

Thanks Joel, so if I remove the side yoke snap rings and remove the yokes to replace the seal, do I need to worry about re-shimming or anything or just put back what came out?  The helicoil repair in this particular situation required a larger diameter bolt than the other three, the coil also appears to be part way out of the hole, that's why I'm leery.  I'll send a picture if I can figure how to upload a compressed shot!

No shims, or other surprises when you remove the snap-rings and yokes. Fairly straight-forward...remove the snap-ring, slide the yoke out, replace seal(s), insert yoke, replace snap-ring. Be sure to keep the yokes on whatever side you take them out from....don't mix them up. They are the same, but they will have a wear pattern on the end that rides against the center shaft of the diff, and it's best to keep them in the original location.
I have been digging back thru my pic files, looking for something that shows the snap-rings, but so far...nuttin...

OK got the crossmember and diff down, here are some pics:  The "somberos" don't look too good on the bottom but the other side not so bad! Guess I'll replace them "while I'm at it".  The yoke and pinion seals do not look to be leaking either (was probably too much grease in the universals) but I'll replace them as well to be safe.

Also...not sure if I should have started a new thread for this, "while I'm at it" I was considering having the trailing arms rebuilt.  Any recommendations?  So far I've been told Bairs and Van Steel have good reputatuions.  Any others?  I'll go with the forum sponsor if all else is equal!  When replacing to I just keep the same number of shims on either side, any other tips?

Mario,

John,

I replaced my side yokes myself and that was totally new territory for me. Didn't get into anything beyond side yokes, seals and cleaning up the inside as best I could. My '78 was 1 of the years that the side yokes wore down pretty quick which created a lot of end play. Picture shows the "C" clips and the mushroom effect of the ends wearing.That was at about 48,000 miles. You can see how much end play I had there on the left as the yoke end wore down. Replaced them, put it back together and its been great since, and no leaks. Didn't measure end play but it was a whole lot tighter after.
Also did a VB&P composite spring i picked up at Carlisle at the same time. I think it was the touring rating , can't remember the lbs. Never told the wife I bought a new spring and within 2 miles she asked me what I did to make the car ride better.

http://i159.photobucket.com/albums/t132/JeffsVette/DSC03587-1.jpg

|UPDATED|4/22/2013 6:29:30 PM (AZT)|/UPDATED|

Great pic, Jeff! Thanks for posting that...I'll be stealing it for future reference.....

The yoke on the left is definitely mushroomed, the one on the right has just about worn all the way down to the snap-ring. Once they wear down that far, the snap-ring can pop off, and fall down in the gears, doing some major damage....as well as allowing the yoke to slide out on hard turns....