O.K I'll 'fess up Alvin, I used Glazing urethane in mine too.

Hey it was free!
I've got my 'Thrifty Scot' reputation to uphold.
I 'glued' the lower sash on.
As you'll be aware the pre 51's used a metal frame round the
one piece glass .
I
found some u shape rubber at work and used this for my frames,worked like a charm!(I've got tempered glass so I could beat on it a bit heavier.)

Not totally original,but then again neither's my truck.