what size should be used for the seal in the rear window?
I picked up one at NAPA that is 5/16" diameter. They don't make a 1/4" there and I was thinking it should be 1/4"? or is 5/16" ok?

1/4 inch butyl tape. I have written some excellent installation instructions (if I do say so myself) in the appendix of the "Tech Tips 700"!

Did mine with 5/6. worked fine.

I used 3M FLAPS quality too and it worked fine... extra material = extra hold area

I just checked the factory manuals and they specify 8mm Solbit, which is 0.315". The 5/16" butyl is 0.3125".

I'd say you got the perfect stuff and 1/4" is too thin.

Or... detailed instructions can be found "here" for free.

http://www.914world.com/bbs2/index.php?showtopic=15821