on the EBay rebuild it looks to have everything on it..I noticed the ring gear had surface rust on it which makes me think they may not be new..they come with a oil coating on them that prevents rust..unless it was cleaned off..only worry buying it would be who rebuilt it..the guy selling it or someone else..if you are the second owner since the rebuild the warranty it has probably won't transfer to you..price is highly negotiable if he bought it for his car and now doesn't need it.
Rich

Thanks Rich.  I emailed him and he said his reserve was set at $600 -- which is dirt cheap for what he has there.  But I have not yet removed mine to determine what I currently have - I am hoping I am a 3:70 but I suspect I might have a 3:08.  This guy has this one set up as a 3:90 - this might be too much with my comp cam I have (comp cam's thumpr).  My top end might be about 60 !  haha

Sorry it took so long to get back I was driving to my moms to hit Chip Millers show in West Chester PA..that diff is really cheap..I don't know what year you have but I have a 3:70 ratio and it tops around 145..65 in 4th is 3k rpm..235/65/15 tires..it depends how you drive it..I get awefull mileage though..I would be tempted to get that rear anyhow..can always swap the ring and pinion out of yours into it.
Rich

I removed the differential assembly, drained it and opened it up.  The drivers side yoke has broken in half right where the gears start.  The snap ring is still in place, so that’s why it didn’t make any noise – I was spinning the tire and the yoke was spinning before it connected with the gears.  I don’t know why the other tire wouldn’t spin though?  It’s yoke appears good – I don’t know how to tell if the clutches are gone.

 

So what would cause the yoke to sheer in half like that?  

 

Also, I marked the good yoke and the drive shaft yoke.  I turned the drive shaft yoke about 3.75 turns  for the half shaft yoke to turn once.  Does that sound like I have a 3:70 ?

 

I was going to count gears, but all I can count is that large gear, the rest spins with it so I am not sure what other gear to count to do them math. 

 

I can’t imagine play on the yoke moving in and out would cause it to snap in half.  But I did hear several clunks from the rear within a couple miles of the failure.  So I am at a loss right now, what would cause the clunks and then the yoke to snap in half?  

Look on the outer edge of the ring gear, and you'll see two numbers. One is the pinion gear tooth count, and the other is the ring gear tooth count. Divide the larger number b y the smaller number, and you get the ratio....for instance, if you see 10  41, then you have a 4:10 ratio.
Or...you can simply look at the bottom of the diff housing, and get the diff code from there.

HEre's the thing about alignments, and that causing yoke failure. It's certainly possible, but I'd say very rare. Ya gotta take into consideration the design of this suspension. The halfshaft IS the upper control arm/link...anytime the car is on the ground, the weight of the car is pushing the yoke into the diff. The only way you could get the alignment off far enough to pull the yoke out, or put undue stress on them, would be to bend the crap out of the lower strut rods, but then the car would be very un-drivable.
Of course, if you are cornering pretty hard, or at high speeds, the pressure on the yoke will be less, but still not enough to pull the yoke outward enough to create an issue.
My thoughts on that yoke failing as quickly as it did was it was prolly just a bad part to start with...that's just my opinion, as I haven't seen the yoke, nor did I see it before it was installed.

What year model car is this, anyway? I keep forgetting, and it's not listed on your profile...

Give Jim Stevens a call, he is a suspension specialists. His prices are resonable and stands behind his work. Lots of C-3 members have had work done by him. His #608-365-0911, hope this helps and saves you some money! Tell him your from C-3VR!

Here's what was found on dis-assembly of the diff. The yoke on the far right is from the driver side, the one in the middle is a new one, and the one on the left is from the pass side...it was about to let go, too! The second pic shows how twisted it is. Apparently, the reconditioned yokes that had just been installed were not heat treated properly, and that's what caused the failure...

 Clarification: John was having trouble posting the pics, so he sent them to me, and I'm posting them for him.

  Adams' Apple2010-11-12 06:02:45

Nice! Dare I ask where the broken parts came from? Glad to see Joel ended up with it. How's the rest look inside?
Rich

I bought them from Eckler's.  Not sure if the blame for faulty parts can be placed with them, but I will say that I called them and they are taking them back with a 100% refund.

Glad to hear Ecklers is standing by their product..how is the vette shop? Not to far from my house but I haven't been there..is it nice?
Rich