Roo,
figure that time to do the metal work including the filling and sanding prep for the bagging. Bagging itself is relatively quick but there is a 24 hour setup time in order to unbag the part. Yes those are 73 windows, the change is in the extension of the sail panels. However I just got in some 72 windows and the actual difference is ONLY in the latch and the location of the drilled hole in the glass. the curve of the window and everything else is the same. In 73 they went to a smaller and plastic latch system to save money.
Andrew