Grigg
This is interesting There is a steel plate 11" tall and 3/8 inch thick rhat runs from just behind the front rearmost shackle to the rear frontmost spring shackle. the plate is formed/ bent well to the frame taper and the bolts holding it on look to be old school the cab and other attached items go through the plate, otherwise not counting the plate the frame is 7". Have you ever seen a modification like that before? the way the plate is tapered at he ends and the quality of the work seems professional. It has a Thiele dump bed made in Johnstown PA, had to be prior to 1966 to have been made at that location. The truck was assembled in Ohio.
Thanks for your feedback