Jon,
Do you have a 1954 Chevrolet Truck Shop Manual? It is a very handy item, if you plan on working-on and keeping the truck for a while.
The rear corner glass/windows installation is quite similar to procedure for the
rear glass/window. Note that the above link is to the 1954 Chevrolet Truck Shop Manual. This might save you having to buy a manual. Also, it has been nicely indexed with links to each sections menu. (thanks to Keith Hardy).
Tim