bigBob,
The 47 and 48, had the gas tank mounted between the frame rails, behind the cab. The fuel filler neck, came out the right side of the bed. Starting in 1949, they mounted the gas tank, in the cab, behind the seat. That continued at least through the early 55 AD. However, the 54 and 55, have a different bed, than the 47-53. You probably already are aware of this. In the event that you are not, the 3100, has a short bed. The 3600 and 3800, both have a long bed. The wheel base, on a 3600 and 3800, are about 9 inches longer than your 3100. That would be a major undertaking to convert yours. To fully answer your question. The tailgate and the front panel should all be the same for 47-53.
In the event that you are just not able to find used 3100 bed that meets your expectations, you might take a look at Mar-K, They manufacture a really nice reproduction bed. They even use one of the original tailgate stamps, from one of the old factories. My original bed was beat. So, I purchased one from them. Everything looks right and it fits right. Just something to think about.
Hope this helps. Good luck with your restoration.
Rugo
