Hello! this complex question. Here it is necessary to think ...
Your post makes no sense. What he was talking about is the POS pot metal quick disconnect fitting that threads in to the intake manifold and welds itself to the manifold, then rots out from the inside.
I would have suggested yanking the intake, breaking the POS fitting off, then trying to knock out as much of the rotted nipple as possible, then run a properly sized tap through the threads of the intake to get the rest of the pot metal out. Then waltz on down to your local GM dealer and by that same fitting, but tell them it's for a 96 Caprice. GM used steel fittings on the Caprice, and pot metal on the trucks and Tahoe's.