Setting material for CCPU rear window

[wrndln]

When I purchased my 29 CCPU, it had no glass or setting material in the rear window. I haven't been able to find out if there was supposed to be a rubber channel or something else around the perimeter of the glass used when installing the rear glass. According to the Service Bulletins, the glass should be 3/16" thick, not 1/4" like the door glass. I plan to use tempered glass as it is much stronger than laminated glass. If someone knows what material was originally used, please post what it was,
Rusty Nelson