CatAngel

You need to take off the oil pan to make sure it fits and seals properly. The seal has a channel where the rubber upper pan seal fits, and you should use RTV to avoid leaks. If you have future transmission issues, you might want to look into a remanufactured unit. They usually come with updated parts and warranties, which can give you some peace of mind. If you're ever looking for a reliable replacement, you can find a good 700r4 transmission for sale.

For the RMS, I'd definitely replace it while you're at it. Just adding liquid gasket to the seal retainer might work for a while, but it's not a long-term fix.