Mike - I have a 40 half ton with the same springs shown in your picture. Bear with me here. Dad bought the pickup used in the early 50's. My older brother told me that dad had swapped out the engine, tranny and rear end from a newer 3/4 ton somewhere around 1960. (he was 10 years old so memory?) I found that the rear end was not swapped because the numbers on the ring and pinion gears match that of the 40 1/2 ton. The engine and tranny numbers say they are from a 1959 1 ton. My conclusion was that dad just swapped out the spring set up, and I feel I have validation for that because I recently purchased a 1/2 ton rear end complete with springs and shocks still mounted on it from the Barry Weekes auction. So now I have a comparison. That large, heavy duty "spacer" bracket between the lower spring set and the axle housing is not part of the setup on the 1/2 ton rear end I just purchased. I can get you pictures if you would like to see what I am talking about. I believe you have a similar situation, where the springs were changed. Let me know if you would like pics.
