We have found it very difficult to put a one piece or V-Butt glass in any truck that came with a roll out windshield and make it look decent. There are gaps where the roll out mechanism fit and also a big gap between the frameless glass and the dash. One can black out around the perimeter to hide some but the big gap from glass to dash is still there and all the roll out hoels need filled and smoothed. Here is a 1940 with a V-Butt and a 1948 with a one piece. Note the 40, though a nice truck, the windshield around the edge is not so nice while the 48, which did not have the roll out windshield, looks quite good.

http://s32.photobucket.com/user/coilover/media/StudeJustins40CougarCat004-1.jpg.html

http://s32.photobucket.com/user/coilover/media/onepiecewindshield001.jpg.html

Evan