The frames are not the same, the front fenders are not the same, the grilles are not the same the cabs are not the same, the beds are not the same. But on the other hand if the 54 is in good condition, the front clip from a 51 Chevy will fit, the door catches will have to be changed to accept the earlier doors and the engine cross member may need to be modified to fit the chevy components ( this may mean modifying the radiator to accept the longer GMC engine)
54 sheet metal is a little bit harder to find in good condition than the 48/53 fenders. Look in the gallery to see some of these differences.
