I received all new glass from a supplier and stated to install. Front and corners went on pretty good, the back window was a different story. It looks like the glass is cut too small. I plan to go to local glass shop to get one cut to fit better. Question is there a rule of thumb for size of glass so that it fits the opening and rubber seal correctly - 1/4 inch or 1/8 inch smaller the opening in the cab? Any thought greatly appreciated.