The deep pan is not the way to fix your problem! The seals are easy to change, just get the (KD) tool (Anderwh) listed and do it in the car. Drain some fluid out prior to doing it so you don't get covered in fluid. If you don't want to buy the tool, use a small screwdriver to pry out the old seal and a deep socket to hammer in the new seal.

Next time you need a small seal for your transmission, go to you local trans shop, they should have plenty of them.