We have a M2A1 with a AMC 360 V8 in it. It also had the Tranny and T case replaced. I will say that she has the sound of a early 70's muscle car. As for speed? well you are still limited by the front and rear gear ratio. As we don't have a working speedo, not sure what she gets up to.The halftrack came this way , and we are gonig to be putting an orginal 160 and tranny/tcase back in. This config now leaves us with NO hand brake. So if we lose brakes...downshift quick !