Question about rear window
 

I've got an 85 d100 that had a flat rear windshield, but I managed to get ahold of a sliding back glass from a 70s truck, but I can't get the new glass to sit tightly in the cab, the seal appears too large for the sliding glass and there are gaps. Do I need a specific seal for the sliding glass, or did the size of the rear windshield change over time?

Those years are 2 different Cab Styles... I dont think the 2 are swapable to my knowledge....

Ah, gotcha. Figured it was worth a shot, they're similar in size and shape, but the 70s glass is about an 1/8th inch smaller all around.

The sliding rear glass was so popular at one point I think they got installed in most new pickups. We were installing sunroofs a couple a week also.

To my knowledge it has more to do with the rubber seal than the window. I recently restored a 72 D200 and was going to reuse the rear window glass, so I ordered a new rubber seal from LMC Truck that was suppose to work for 72-90’s D W series trucks. The seal was the right size for the outside but the glass was too small. I had a piece of glass from an 85 and it fit right in there as it was suppose to.