once again my friend. there is no difference in the G1 master cylinders from 87-90 with abs brakes and no difference in them without abs from 86-90.now you can't use one without abs on a car that had abs because all the fitting and connections are different and there are more lines that run to the abs unit from the mc.as for different part numbers, could be a different supplier for a different year but trust me they are interchangeable.