Audi trans propshaft seal

I have a 2000 Audi A6 4.2. I’ve noticed a few drops in my garage for over two years. The dealer only recently told me that I had a leak in the transmission propshaft seal - but they said they couldn’t tell me how fluid I had lost and that I needed to replace the part. Is this true? If I need this repair, how much should i expect to pay?

If there’s a dipstick for the transmission of differential that’s leaking, and there should be, either the dealer or you can check the dipstick to tell how much fluid has leaked out.

The rear differential may not have a dipstick, but it has a drain plug and a fill plug, and you fill it to the bottom of the fill plug opening. It’s not rocket science. The dealer is playing games with you.

Transmission repair on an Audi will be expensive, especially at the dealer.