Just reading an article that Bob Adler did from 1998 that ran on the Chevytrucks.org site entitled "Bob Adler on rear main seals".
According to him and fel-pro if ya drop the crank even the slightest amount your gonna have a leak at the front seal. I taint about to take the whole front of the engine apart at this time to replace the front seal, so that's out. He doesn't specifically address the upper half of the seal, only installing the bottom half rope.
I'm now thinking about just pulling the pan and rear main cap and that should take care of 90% of the leak. Maybe that will improve the oil mileage enough for me to get 500 miles to a quart.
www.chevytrucks.org/tech/bobadler-1.htm Denny Graham
Sandwich, IL
