ok, here is the deal with the RTV on the intakes.
with almost all of GM V6 and V8 engines, if the intake gasket set includes end seals, throw them away !!!!!!!!!!!!!!!! they will defintly leak
use RTV on the corners and run a 1/4"-3/8" bead where the end seals should be.
also as a rule of thumb. i always put a thin film where the water ports are in the head and on the intake too.
and one more thing before i forget to tell you. get teflon sealant and make sure you put some on the threads of the intake bolts. this will prevent oil from coming through the threads of the bolts.
if you look at the newer GM engines, you will see that they use alot of RTV when they assemble them at the factory. i did head gaskets on a 3.1 this past week and the end seals on the intake were RTV . FACTORY!!!!
they use it for everything from oilpan gaskets to valve cover gaskets
hope this helped