I'm trying to figure out what kind of sealer went between the roofrail weatherstrip channels (stainless), and the actual metal roof on my '69 Mach. The car had already been taken apart when I got it, but the weatherstrip channels had been poorly cleaned. From what I can tell, the original sealer was a very sticky/tacky black goop that remained pliable.
I thought it might be butyl sealer, but one of my friends in the auto body business said butyl won't compress enough to allow the stainless channels to fit tightly against the roof. He recommended using 3M strip caulking. The only reason I'm hesitant to go that route is that I'd need to buy a ton of it to make a wide enough bead to seal the whole backside of the stainless channels (it appears that the original sealer covered nearly the entire backside of the stainless).
I've used the roofrail foam in the past, but I thought that was more of a '65-66 thing; I had some foam leftover from my '66 fastback restoration, and it looked nothing like what was on the Mach 1 stainless.
Any ideas or suggestions on what to use? This is a Metuchen Mach 1, built on June 5th, 1969. Thanks!