The first time I assembled my 54 Dodge pickup, I used a calk rope flattened out. That didn't last a year. The next time, I just bolted the stuff together, and that was the way it was when it left me 7 years later. I really didn't hear many squeaks, but the truck had a rumble that probably muffled me from hearing any squeaks.

Butyl might work OK, at least it won't squish out very fast. Gene