You said you sealed between the glass and gasket, did you seal between cab and gasket? The picture looks like the bottom corner of the glass may be a trifle small, which is not unusual. We used to work a piece of screen spline into the groove to push the gasket out. This would probably be next to impossible at this point, depending on how well the silicone on the glass stuck. Originally the sealant used was a caulk that stayed soft for a long time (most was labelled "bedding and glazing"}. Several years ago the FMVSS was amended to require urethane be used to retain any stationary glass in a rollover. This is probably why the shop mentioned used it. Unfortunately, it can be next to impossible to remove the glass and save the gasket when this is done. I haven't been involved in the glass business for 4-5 years now, but a couple weeks ago I was able to find a tube of "bedding and glazing" made by a Canadian company at my local NAPA to use on my nephews Chevy II. Any silicone used for these purposes should be automotive type containing no acetic acid (the vinegar smell) to prevent metal corrosion. Silicones were used on school bus windshield installs since they needed to be able to be kicked out in an emergency. Hopefully some of this long winded post may be helpful to someone. John