2 Piece Rear Main Seal

[75stepside]

I completed a 4.5 year restoration in July of 2004. My 350 was totally rebuilt and reassembled using a Felpro Gasket kit. It appears that my rear main seal is leaking. I'm looking into changing it, but am un-certain which rear seal i need. According to www.partsamerica.com, I have 3 options:

1. BS40013 - rubber; two-piece; double lip
2. BS118291 - rubber; two-piece; offset double lip
3. BS40655 - rubber; two-piece; single lip

First, what seal do i need? and Two, in reading some general internet stuff, some guys say you have to pull the engine to do this!?!? I seems to me that removing the oil pan, the oil pump and rear main bearing cap would be enough?

any advice, opinions, etc. - greatly appreciated!