I'm one of those someone's that did it with the rear window in our Uhaul
. I had to widen the opening by about 1/2" each side and round the corners a little. Also had to put the clamp ring on backwards. Scamp
did a great job boxing the windows
. I got the rear and one side window, $160 for the rear, $152 for the side, shipping was $60. You really can't tell how it will fit until you get your old window out. I have the following measurements that I took for the rear. My original opening was 41 3/8" wide, 18 1/8" high. The Scamp window needed an opening of 42 3/4" wide and 18 1/4" high with a 3" radius corner. Scamp sent the clamp ring and some sticky back foam tape. You're probably better to use the butyl putty tape rather than what Scamp provides. I couldn't get the window flange to draw up tight, and it probably didn't leak because I also used some adhesive sealer too.