I just finished a 3 to 5 window conversion for a friend on a "51 1 ton.
Fortunately I was able to find a salvage cab and had them cut out the corner sections with a chop saw.
Then proceeded to separate the inner and outer sections by drilling spot welds.
I used just a small section on the out side around the windows'(about an inch) and put the inner in at the factory seams.
It involved a lot of measuring and fitting, but it turned out beautifully.
The outside sections were welded in with a Lenco Panelspotter,
Makes two factory type spot welds from the same side.
I was able to buy the cab sections and the glass for $250,so it was a big savings over new pieces ,and retained the integrity of the cab as well.
