The forend lugs are different between the Trojan and any other hammerless Parker. Also, the doll's heads are different as are the recesses in the frame that accept the doll's head. The Trojan, up to the late 1920's has a rounded rib extension (later Trojans had none at all) while other grades had a "doll's head". These are the major obstacles and would present very costly alterations in order to fit Trojan barrels to a VH.