2002 tahoe LT rear main cover gasket??

[Tahoe2002LT]

I have a 2002 chevy tahoe LT.. I have have replaced the oil cooler seal, rear main seal, oil sending unit and oil pan gasket. Now it leaks worse than it did before. The mechanic replaced the rear main seal a second time and it still leaks. He now says that there is a crank shaft seal behind the rear main that is the problem. I hear the 1999-2002 have problems with the rear main cover gasket leaking. Has anyone ever heard of a seal behind the rear main seal on the crank shaft? He's telling me he has to rebuild the motor or that I need to replace the motor because it has too many miles on it.
I know he didn't replace the rear main plate gasket. I hoping that this is the problem. On a side note the motor sounds great no knocks or grinding. I'd hate to spend money on something that doesn't need fixing Any info would be great. Thanks.

 

[Tahoe2002LT]

The leak was the rear main cover gasket. Holding oil after 400 miles in 2 days.

 

[Tahoe2002LT]

4 days later still holding oil.

 

[afpj]

Curious as to where you were seeing oil? Dripping from oil pan drain bolt because of runoff, or dripping somewhere Else? I thought most mechanics would change that rear main cover when doing a rear main bearing seal since it's right there?