Hey Guys, where's the best place to get a rear window rope seal for 68-70 B-body's? Does anyone know the length required for a 69 Charger and 69 Roadrunner?

Thanks !

They come as an universal kit and any glass shop or parts store should have them.

Automotive paint stores have what you need.

It is a 5/16 butyl tape,available from 3M and other companies too.The 3M package even comes with the rubber blocks for the glass to sit on. Be sure to use butyl tape primer on the pichweld - NOT urethane primer ! Butyl primer can be hard to find nowdays,but it is available and necessary.
I like to use the square tape like OEM,but the round will work too,just add some glass sealant around the edges when all done,and make absolutely sure your window trim clips are in place with the correct shallow head screws before you install the glass, or you will be very angry !I prefer to use original clips since the aftermarket ones always seem to be less like spring steel and more bendable than the originals.

Thanks guys !

Anyone know the length required, or does it just come in a standard length roll and you cut to fit?

Napa. If I remember right one roll does a window. I also used 3/8 not 5/16 on my 69 b-body rear(had to redo)so the trim would lay flat.

I always paint mine before I install the glass... I never even hear of butyl primer.