rear mani seal

Step one, get a manual of some sort. Preferably a factory service manual (there are reprints on eBay). This should answer a lot of questions about what needs to be done to remove the pan with the engine in the chassis. It is a pain!

Next, depending on the year of your engine it will either have a neoprene lip seal or the old graphite impregnated rope seal (probably rope on a 65). Either way you can generally only replace the lower half without pulling the crank. I like the rope seals better, but they are best replaced with the engine out.