I have the Diamante 3.0 in my '91 4x4 MM and it's great. It's a higher compression engine, so it clearly has more power than the original and gets better gas mileage. The best I ever got with the original was just over 20 mpg but I have gotten 24 with the Diamante version. I picked up one of the "Imported Low Mileage Engines" and needed to swap a few parts from my original but am using the original ecu. I would highly recommend going this route.