the frames are the same, however the hubs are different, they use different offset to put the wheels in the proper place. there are companies out there that off adapter kits to take care off this problem I had a customer several years ago use a set of them on a F250 to make it a dually they seemed to work fine for him. I have no idea what they cost. the fast option is to just pick up a dually axle and bolt up? sorry your so far away I have extra 4.10 axle dually axle setting out here I do have a set of spare hubs and drums however I would put on new drums and brakes while you have it a part
good luck.
2003 CHEVY 4500 DURAMAX/ALLISON 14'
SERVICE CRANE BODY 16,500 LBS 14.5 MPG
1998 K3500 SRW CREW CAB TRANSPLANTED 6.5TD ELECTROINC INTO, HEATH COMPUTER, 40+HP INJECTORS, 4" EXHAUST, VACUUM ELEMTINATOR ON TURBO,UPGRADED COOLING WITH ALL GM PARTS,NO VACUUM PUMP, SST OIL COOLER LINES MADE LOCALY FRACTION OF THE COST, 3" TOURBO/BOOST GAUSGE ALL IN ONE, ADDED GEAR DRIVE GREAT HELP WITH STARTING TIME DOESN'T JUMP AROUND ANY MORE, INTERCOOLER 3" INLET AND OUTLET COOLER 12x24x4, ALSO ADDED MANDEL BENT CROSS OVER, HAD TRUCK REPAINTED AND OPUT ON ALUM FLAT BED