I have a 85 K5 that I bought back in November. The guy I bought it from wasn't sure of the lift height saying he bought it that way. It has 315/75/16 tires that have plenty of room. From the top of the front axle to the bottom of the frame is roughly 11" and center of front hub to fender lip is 25.5". My best guess would be 3"-4" but what do the experts say?
