Thanks. What kind of hauling and fuel inprovements did you see?
Well, I really don't haul that much. If you saw my signature, the GV is on an F150... an old one none the less. When I did haul something before the GV, I was going up a highway grade at about 45 MPH, 2nd gear & engine going 2500+RPMS. I'm sure if I split 2nd, I could have been going 45 at much less RPMS or going 50MPH at the same RPMS.
After install, I noticed a small improvement. Fuel economy went from about 15MPG to just under 17MPG highway. Both the GV and US Gear advertise between 10-25% depending on driving habits. Then my distributor went T/U (and I thought it was the carb)...so I messed w/ the carb fuel/air ratio. Right now, it's running WAY rich...... haven't had time to redo. Right now, my fuel economy sucks on my I6 300.
Hauling improvement you man see depends on your specific info, as in your axle ratio, which transmission and how much you plan to haul. If you have 4.10's, and an E4OD, you could actually run a double over drive and drop your final ratio to about 2.33. It would keep your RPM way down running at 75MPH empty. The 4th gear in a E4OD is a deeper reduction vs the GV unit. The E4OD is .78 ratio while the GV is a .73. Granted, not much, but you could in theory lock out your factory OD and tow w/ the GV unit (so the tranny doesn't hunt). But, there is two trains of thought on if you should or can tow using the factory OD. Some say you can, others say NO.
There was a member at the other Ford forum (thedieselstop) that had TWO GV OD's if I recall the pic right. I'm sure they belong to this one too, but I just can't recall the user name. It was on a Ford crew cab so there was enough frame. For some reason, I think it had the ZF tranny also.....not sure.