I see what you’re looking at Dan but as is true with cross referencing parts in later publications of the books, it doesn’t always seem to be true to what was original. So I do not understand why they included a 36 on your picture as the model is listed are ‘37’s. To the best of my knowledge. The 36 whether high or low cab, all had the tank between the frame rails in the back. The 37 regardless of the size and there was only a half ton and one and a half ton and variations such as canopy, cab, only, and panel, all had the tank under the seat with the 5050 split to be able to get to the bung. Btw, there was never a high cab 37 as 36 was the transition year early high cab, late, low cab. In 38 and possibly a few very late 37 the seat riser was revised to accommodate the exterior filler behind the passenger side door in the cab. So to answer waveski, yes, the 37 was the only year for the filler bung to actually be inside the cab under the seat.
