3/4 or 1' butyl tape?

I like the black Butyl tape 3/4 in wide because my window trim is black. Also the tape is a little firmer and less sticky than the white tape, but I have used both and both work. After you clean the old tape off dry fit the window without the inside retainer frame and make sure the cutout in the wall is even around the frame itself, you may have to put extra tape in areas where the opening is too large or cut out is uneven. The window will shift down due to the movement of the sidewalls and vibrations on rough roads so putting spacers at the bottom of the side wall sill will prevent the downward shift causing a leak in several years. If you install it correctly the seal will last for years because the tape will stay pliable. The two windows that I had the most problems with were for leaks were the driver and passenger windows. The ones in the rear have never leaked in 25 years of service.