I'll tell you what I did. I know its not a popular idea. After failing two times with the intake manifold still leaking. I went to advance auto, bought some thin gasket material, like an 1/8th of an inch thick. First I cleaned the block and intake mating surfaces with acetone, wiped it with a damp rag, let dry. Cut a piece of gasket material out for the front and back. Used the black rtv, sealed around the intake ports. Set it straight down on the block let it set for an hour and torqued. I know alot of people will say this is not necessary, but I have no more leaks. Thats all I care about.