you need a wiring diagram and a manual for a 74 140, this will explain everything. you might need the fuel tank from the 75, not sure about that, but you will need a feed pump in the tank regardless of which tank you use. everything else between the tank and the head should transfer. intake, air cleaner, fuel pump and accumulator, etc. and, yes, kjet injectors wear out. the seats and springs inside get worn. buy a kjet fuel pressure kit, too, so you can see if the pressures are ok. pressure is everything on a kjet. me, it's too hard or i'm too lazy to change a djet to a kjet. the money you spend on the changeover and getting it running will pay for alot of fixes on the djet..