I drive 90% of my annual miles (about 40k) empty on the highway at 84 mph (9 over posted speed) . So in an effort to save on fuel I have purchased a propane kit and $3k in tranny upgrades from DTT now I am thinking auxillary overdrive. Anyone running one on the 48re? How much RPM drop and increase in MPG? Any good or bad reports on "Gear Vendor" or "US Gear"?

 

I think the GV unit is a .70 OD and it should drop your current RPM at any speed by 500 RPMS. I have one on my 87 Ford and it works very well, and really help with fuel mileage. Scotty