Other than the gearbox (260 - with engine speed and TDC sensors) what else needs to be changed. I am putting a 2.5 into my E30 pre F/L 320. First and biggest problem is finding a gearbox that has the sensor ports in the bellhousing. What else do I need to change ie. complete wiring loom or can I just change the engine loom. From what I can see there is no real need to change the whole lot. The only unknowns that I can find is the fuel pump relay and main relay. The other is the rev counter. The computer picks up the engine speed via the bellhousing mounted sensor but how does it get the info to the rev counter. Obviously the computer will have a wire leading to the dash but is it a plug and play conversion (will the pre F/L dash and wiring match the Motronic computer loom).