[Driver_WT]

Given the fact that you are on an 86 frame, the question may be what is your reference point for the cab height off the frame front and rear. If you are measuring at the cab mounts, they may not be in the same place/height as the original. I sometimes find it a challenge to get a measurable reference point on these trucks. Ultimately, you will want the bottom of the door to be parallel with the running boards, so maybe make the bottom of the door to be parallel to the frame.