The Stovebolt Site Forums The Shop Area Paint and Body Shop 1946 chevy pickup window frame.

The metal frame X-section is pretty thin - not sure you could remove enough metal and rebuild with fibreglass. There is a splice bar that fits in the lower center bottom frame area which needs to be tight to avoid too much flex when you crank open the window. I ended up buying a new frame which is expensive, but mine was pretty far gone. You could always try the FG solution, the buy a frame if necessary.