I had my 1970 rear glass professionally installed. The guys super cleaned everything, used correct pinchweld primer, used 3/8 butyl ribbon, set the glass and all was good. Then I started working on setting the trunk lid and filler gaps and such. In doing so I removed the 2 small spacer blocks and forgot to put them back in. Over the next week the glass "slid" down until it is touching the filler panel and completely off the upper pinchweld butyl tape. YEP it came off the butyl completely and like it was never stuck. No residue on the glass and the exposed butyl isn't even sticky. So I am rethinking the re install. Has anyone used the special modern urethane glass adhesive on old school cars?