I liscenced and insured mine as a 91. I used the 91 dash (where the VIN tag is), My insurance agent said if it where totaled it would be easier to get paid on a 91, the rate was same for an 84 for full coverage because of parts availability. As far as switching cabs vs. drivetrain my donor truck was a 2x4 1 ton cab chassis with 4. 56 rear. So to get a 4x4 with 3. 54s stretching the frame was my best choice. I have a friend that stretches big truck frames for a living so my frame is stronger now than ever.