I've replaced the rear shaft oil seal on my T56 twice now, and I still have a leak. Oil is sprayed all over the underside of the car starting from the output shaft on the trans. I just put the shifter on (when I swapped the LT1 in) and RTVed it, so that doesn't seem to be leaking. My question is, are the seals for the A4 and the M6 different? I can't see how they would be, since the driveshaft is the same size. It's just that when I went to the auto parts store the 2nd time for this problem, they said they didn't have an entry for the M6 seal, but they did for the A4. The one they gave me looked the same as the first one I replaced, but they both didn't have a sleeve coming from the back of the seal like the original did. Any thoughts as to why its still leaking?

 

Are there any other seals around the rear seal that I should check? The reverse lockout looks to be dry. The speed sensor is below the output, so I don't know how that would spray all over the underside.

 

I had the same problem earlier this summer after I took my driveshaft off to add a safety loop. When I put it back together it leaking out of the rear shaft of the transmission, very obvious even with the over spray all over the undercarriage. I went to the Checkers Auto Parts and they said they didnt have a seal for the M6 only for the A4. The dealership quoted me a seal for $25-$30 price but they said that a local auto parts store should carry it cheaper. So I checked with Autozone and got one for less than $5, but had to show them my old seal first so they knew what it looked like. Anyways, I added a little grease on the outside of the seal and tapped it back in with a large socket. I havent had no problems since, but I could see how if you didnt install it correct the first time it could get damaged and leak again. You might want to recheck and ensure you sealed the new seal properly. As for the seal on a A4 and M6 I found out they are the same.

Mike