(Years ago), there were so many people having problems with the LOWER intake gaskets that GM did a factory recall. At that time, I owned an Impala with a 3400 (different intake configuration) and my Indy mechanic told me it WASN'T on the recall list. My advice to you (which you are free to disregard as being worth what you've paid for it) is that you're not fixing what isn't broken. You're avoiding a distinct possibility of hydrolock and wasting an engine over a KNOWN defect in manufacturing. Perhaps ask yourself "Why did GM revise the lower intake gaskets?" If you start rereading your own thread, how many users have steered you to GM 89017825 to use for new gaskets? Why would we all try to steer you wrong and yet in the exact same wrong direction? The answer sir is that several very knowledgeable and capable (NOT ME) users are very much attempting to HELP you. Trav, doublebase, and Lubener are assets on this board.
If you're under the hood, look at the engine on the driver's side, just above and to the left of where the coolant temp sensor is...the lower intake gasket is visible right here at the corner (about a half inch to the left and below the thermostat housing). Clean the gasket here with some carburetor cleaner. If the cleaned gasket is black, it's OEM and failure waiting to happen. If it's grey, it's aluminum and has already been replaced with GM 89017825.
Watch this guy do it from beginning to end in just over 20 minutes:
Then you can search for the operation on Youtube and there are myriad videos, this is a known common problem: https://www.youtube.com/results?search_query=replace+gm+3800+lower+intake+manifold+gasket