Look at your rear axle, there should be a sensor wire coming out of it near the ring gear. If that's the case, you should be able to convert no prob. If you have sensor wires out near the drums, you'll have to find rotors that have the little reluctor teeth cut into them. Plus they'll have to be the same size, and number of teeth. If there are no wires to the rear axle, it meens the ABS sensor is your speed sensor which is located in the trans. Convertion is Ok in that case as well. Don't forget to put an adjustable proportioning valve in, to squeeze off some of the rear brake pressure, or the first time you hit your brakes at speed, you'll swap ends.
