47-53 Frames are mostly the same there are some small differences like 47& early 48 had a different style of cab mount and some of the early frames had Lever action shocks as opposed to tube shocks, Like the guys said it should be doable if you have one of those early frames you'll need to come up with some cab mounts from a 1/2 ton.
The 54 Frame is also pretty similar with one major difference being that the frame kick up over the rear end is lower on the 54, this was because of the new flat side beds.
Here is the frame checking measurements so you can make sure you are good on what you have.
http://www.mongosgarage.com/tech/FrameCheckingBig.jpgThe 1/2 Ton frames Taper all the way back (as in the drawing on the link) as opposed to the bigger frames taper to a point then are straight and 36 or so inches wide all the way to the back.
Mongo
