to check the lower, otherwise if you didn't see any evidence of a leak on the upper to plenum gasket after removing the plenum, you wouldn't know for sure if it wasn't the lower gasket after all. I'll do the same and I'll use your example. Also, I think a little sealer help is a good idea. I've used the "brown" before, sticky..stinky but very good. A little goes a long way. Thanks for your help.