Just purchased an 85 blazer that i'm am restoring. It leaks oil(only when running) from the front and rear parts of the oilpan. I'm confident I can do the oilpan gasket, I'd like info on the rear main seal. My engine has 150k--I think. All the manuals I have read indicate 2 types of gaskets, rope neoprene. Any favorites? Pro's con's? Thanks for any info. P.S. The Idea about tech articles for the forum would be sweet!