They can run the same calibrations. The 727 is water resistant, the 730 is not. The mounting, and connectors aare entirely different. Grumpy | ok I'm a little confused isn't the 7727 the same as the 7730 except for it | goes in the engine comp? in one of these repy's some said 7727 7128..... | anyway I should be able to find one in a y body or w is this correct?? | | -Brian |