Filler
To be specific:
You are looking for DEVCON ALUMINUM PUTTY (Epoxy Compound) Stock No. 10610
I have not used it on any Buick stuff but with great success on intake runners on M/Cs. With the M/Cs, I put an aluminum plate (secured with a aluminum sheet metal screw) with the putty under it as a filler. After results were positive and the only way to remove the material was with a grinder. The material is NOT
cheap...