its actually 49-53, 47-48 gmc had a slightly different grille and bumper that mimicked the larger gmcs.
its preference, the chevy front end will fit a gmc that doesnt have a gmc motor any more, otherwise you will need to make accomodations for the longer gmc motor. from what I remember yours already has a chevy motor.
you will need the WHOLE chevy front end. also, you will need you make the chevy core support mount up to the gmc frame crossmember which is different. the gmc motor is about 5 inches longer.
I personally like the gmc front ends over the chevy. my 47 was gorgeous with that big chrome grille and I have a 49-53 GMC front clip in the classifieds that I will probably end up keeping and finding a cab for because I like them so much.
