Drive train issue

[Clifford69]

Here's my problem: I had my TH350 transmission rebuilt about 3 weeks ago by a local shop, everything was working great until I was driving through Atlanta yesterday and my transmission suffered complete failure (I had to step on the brake otherwise it would roll backwards no matter what gear I was in. A few minutes later it wouldn't budge no matter what gear it was in). About 30 minutes after the transmission failed I noticed that my rear differential was leaking where the drive shaft enters. I have had a few problems dealing with the shop since the tranny crapped out on me and I'm afraid that they're going to say that the rear differential caused the transmission to fail. I did a complete service on my rear end when I redid my bed last summer (June 08) and everything looked great (i.e. no stripped teeth etc.). The truck is still in Atlanta waiting for the shop to pick it up (part of the issue with the shop) so I have not yet had a chance to look at anything yet. So...is it possible that the rear differential could have been totally screwed up by the tranny problem or am I eating all the money I threw into the tranny because the rear differential jacked up the tranny? I know this is totally open ended but any advice would be greatly appreciated.