clutch, now tail shaft?

I'm not happy...to say the least. I had my clutch replaced in my '96 T-100. This was after it was replaced by someone else a couple of years ago. Merchant's Tire did the work this time and I've had good service from them in the past, but this seems a little strange. They finished the job, I drove it around the block and everything seemed fine. Expensive, but the clutch felt good. The next day I noticed a little fluid drippings under the truck. I thought maybe it was just some extra that had dripped off something. The next day there was another spot - maybe 4". I took it up to Merchant's and they checked it and say that I need a rear tail shaft seal and oil pan gasket. I know what an oil pan gasket is, but not sure what the "tail shaft" thing is. But, it seems strange to me that I had had NO drips until they did the work on the clutch/slave cylinder. Now they want $535. to fix this problem -- after $1000. for the clutch. Any thoughts? Thanks.

Tailshaft housing is the last part of yer transmission. They might have dorked it when they dropped yer transmission...couldn't be sure. You should be able to do the seal yerself. You could always shop around as well... ;)