i have found out that if the data plate say ministry of supply WV3 it would have been overhauled in the uk by a civilan workshop and put back into stock in an ordinance depot so the MTRS number which i think stands for (motor transport repair shop) would have been the civian workshop number that did the overhaul and also sometimes they might run an asembley line just for engines or gearboxes also not all bikes that went in some didnt come out ie say 50 went in maybe only 47 came out because of the bits that were written off