Yeah, that... my brother has like 6? of the 3-6 cylinder Ford tractors and there's two heights of injectors, he's only bought 3 replacement injectors though for the 4600 but apparently there's only a few different injectors between the whole range of everything... we put one of those injectors from the 4600 in the 7000 chasing an odd miss. The 4600's issue turned out to be in the pump but running Diesel Klean or whatever (grey bottle) fixed that thing right up...