I had the same problem yesterday. Had the 1950 1/2 ton fully loaded with various items to sell at the swap meet. Obviously, the rear was a bit lower than the front of the truck. Twice the gearshift lever jumped out of 3rd under acceleration, and once while cruising. I figured it was because of the angle of the transmission while under under a somewhat heavy load. If it happens again while the truck is empty I’ll know I have a problem to fix.
