Does anyone have any experience with the Ranger overdrive for the SM420/465 transmission? http://www.high-impact.net/transmission_and_gear/rangeroverdrive.htm I have a 1964 C10 with a 292 I6, and the SM420 4 speed box. I am interested in doing this upgrade to make it more friendly for long distance trips, and possibly even some long distance towing. I don't need to hear about the T5 or T56 swap> I understand that this is the more popular route, it just doesn't interest me as much as this overdrive unit does. I like the SM420 unit, and am not very interested in swapping in the newer trans. If you have used the Ranger unit please let me know your thoughts on it. Any breakages, problems, or gripes? I don't mind the separate shifter, or moving the trans back. Crossmember problems, and shifter location are things that would have to be addressed with the T5/56 swap anyways. Thanks!