3-speed manual leaking fluid

Thanks for responses. I went to auto parts store today and now better understand what the seal looks like. Could someone pls advise me on how to remove the seal? It appears that I'll need something approx the same diameter to drive in the new seal - but how do I pull out the old seal without damaging anything else?

Also, will there be a part number on the seal that will help me order the right replacement? (Parts store today told me that there were 3 rear seal options in the book for a 3-speed Duster in 1971.)

tx,
Ken