2.5 rear main seal leak

[boxerdave]

First Nissan in a long time, 2005 Altima 2.5 with 100,000 miles, I was into 510's many years ago. I have developed a pretty good oil leak and my guess is the rear main seal-it is engine oil for sure. It is coating the underside of the car right back to the middle muffler. Seems to be highway speeds are the worst. I have taken off the access plate at the bell housing and while there is no oil on the flex plate, if I stick my finger in toward the engine side, I can find a bit of oil. I did recently replace the crank position sensor but I would guess this is a "dry hole" so O ring intact or not, it would not matter - please confirm. In case there is a crankcase pressurization issue, I did have a look at the PCV valve, it was clean and clear. Is there any other area that could be causing a leak that I might check out? And finally, can just the transmission be removed or do I have to remove both engine and transmission as a unit? Thanks for your input.