The back hatch on my 93 classic wagon was badly rusted when I bought it a few months ago. I found a hatch in suberb condition from a junkyard 91 except it had broken glass. Using the Brickboard as a resource here's how I ended up doing the job:

1. Cleaned up the 91 but left a thin layer of the original black butyl.
2. Removed the glass from the 93 using a guitar D string - very easy - poked it through the butyl and did a back and forth sawing motion trying to remove the window and as much of the old butyl as possible.
3. Once out I removed any of the loose butyl and attempted to make it all approximately the same thickness.
4. Put a bead of fresh butyl mostly on the outside of the existing on the window.
5. Put the window on the 91 frame and eyeballed the centering, applied some even pressure and put it flat in the sun for awhile.

Keep in mind this is a $500 car. It being sunny and about 65 degrees seemed about right - I think it would be harder in colder temperatures.

When I installed the new hatch it fit perfectly and latched nicely - pretty good for a hatch that came from a junkyard car that had two other cars stacked on top when I found it.

Ron 93 245
near Brantford, ON