I haven't tried it yet, but I am heavily considering it for my '04 Diesel Ram and my '68 Barracuda. In the Ram with 4.10 gears, even in 6th it is turning the motor too high for sustained highway use. It has more than enough guts, but the mileage drops like a rock. At 55 MPH and below it's happy. Over 55 and goodbye $$$. The GV unit allows gear splitting, i.e. 1st gear/1st gear in overdrive, 2nd/2nd overdrive, etc. With the stick shift in the truck, I can see this being handy. With an automatic, not as handy. Now the real question is what rear gear ratio do you have now? If you are still running the stock gears, I do not think you will see much of a difference in mileage. A 2.94 rear gear in overdrive is the equivalent of a 2.29 rear gear. If you are planning a run to the salt flats, that might be a good ratio. If you are running 3.55's, it will drop it down to a 2.77, a nice highway gear ratio. 3.91's drop down to a still highway friendly 3.05. I have a spreadsheet at work that I was playing around with during lunch(es) this week calculating RPMs based on MPH, rear gear ratio, and tire diameter. If I remember to send it home tomorrow, I'll be glad to share it with anyone who is interested. Other than cutting the driveshaft, the transmission tailshaft housing is replaced with the GV adapter and the overdrive unit bolts to it. Rob McCall '67 LeBaron, probably 2.94 gears. -----Original Message----- On Behalf Of Damian Justice yessir, you have to cut, or replace the driveshaft. They have under/overdrive if you are intrested in a quick takeoff followed by high speed/low rpm. I am only intrested in low r's on the highway. I guess nobody has tried it yet. ----------------- http://www.imperialclub.com ----------------- This message was sent to you by the Imperial Mailing List. Please reply to mailing-list@xxxxxxxxxxxxxxxx and your response will be shared with everyone. Private messages (and attachments) for the Administrators should be sent to webmaster@xxxxxxxxxxxxxxxx To UN-SUBSCRIBE, go to http://imperialclub.com/unsubscribe.htm