I have a solid 72 bed sitting on my 4x4 that is going to be going away, but it needs some bodywork on the side- it has a dent and tear on the driver's side, you can see the pics in my gallery. If you want it (the bed) you can have it.
A later bed will physically fit, but bolting it up might be an issue, since the 67-72 frame is about 2" narrower.