Gila is pretty good and can be found in some parts stores. Just keep everything super clean when tinting. I always manage to get some spec of dust, a cat hair, or something under mine-- at least one under every damned window! It's a real easy job if you take the windows out first. I took all the glass out of my car when I painted it, replaced all the seals ($365, but $130 was for the station wagon side glass -- rest was for sweeps and channel for all the others, the seals around the tailgate window weren't cheap either!).
One question -- you really have a 61 Studebaker Wagonaire? If so, any problems with the roof leaking? For those who don't know, the wagon roof (rear) slides forward between front roof and head liner, leaving the back open sort of like a truck except you still have the side glass.