Almost every component that is attached to or, passes through the fiirewall has sealant applied to it. The 1969 AIM shows GM Part # 9980664.
Any ideas what today's 3M equivalent or another substitute might be please? I am assuming this GM # is now invalid. My search engine revealed nothing.. (It's probably a Ford!)

I assume this is a sealant that would not harden and remain plyable like caulk perhaps.
Thanks. :)

Oh, just to clarify, I am NOT talking about seam sealer. See page 31 UPC1-A7 of the 69 AIM.