i thought they were the same but if i put bosch on its say 1in over to the rt against my cav one, took it off a scrap earlier engine, will not operate in this position, i locked everything so pully does not come out of mesh. my mate works at dale diesels where they do nothing but repair pumps and fit them, says they have tried before but wont work,i can have one for 100pounds but will not run it. i bet there is a way as it fits but timeing way out and not enough turn on pump. on my 2 engines thought the studs looked the same but on measuring 20 times realised they were not in the same position, but to look at it they are