According to the 51 Truck info from the GM heritage site, the bed floor of a 3604 model pickup is 5 inches above the top of the frame at the centerline of the rear axle. Add another 3/4 inch to that to the hole and you're going to be pretty dang close for the height of those second from the bottom holes. I just looked at my bedsides for reference, but don't have the side angle so I'm guessing on the distance between the bed floor and the hole. That's the best I can do at this point.
Last edited by klhansen; 06/28/2017 7:08 AM.
