I'm in the process of reinstalling the back window in my 65 and when I checked with the local body shop supply store the asked whether I wanted square or round butyl tape. I'm pretty sure the original was round but wasn't sure if there may be some advantage to square.

Also 5/16" is what I want for an original window right?

Thanks

Jeff
65 Chevelle

It's kind of a squared oval in cross section. If you stick with 3M you know you're getting the right stuff. Yes 5/16" is what you want for the rear window, at least it is for a '68-'72. Maybe someone with experience on a '64-'65 will chime in.

Ya got it Right Von.. it's oval and 5/16 for stock thickness glass. Aftermarket thin glass you use 3/8 dia. 3-M ..

Sorry to butt in, but is Pinkington glass the right thickness for the 5/16" size or would I have to go for the 3/8's sealer? thanks. Eric

Also, 5/16" is also correct for 64-67

I installed Pilkington (repro LOF) rear glass in my '69 and it was stock thickness, so 5/16" was perfect.

Thanks Von, I was worried there for a minute.