Overdrive transmissions
JM, As one of the other guys said US Gear has so far decided not to make an adapter for their OD trans for our G56 equipped trucks. I have emailed the customer service boys at US Gear a number of times and they don't seem interested, saying that the transmissions keep changing so fast in the new trucks that they can't keep up with them.
I had asked them about an adapter to mount the US Gear OD behind the T-case (they normally mount their unit between the trans and the T-case) as I don't want to rework all my driveline to install an OD unit.
I have owned a Gearvendors unit and although it worked fine, I was always concerned about the amount of clutch material in the oil when I changed it.
I also didn't care for the little piston pump that provided oil pressure to actuate the clutch, which was driven by the output shaft, so you had to be running above 25 mph to get the unit to shift into overdrive.
I tend to think a lot like you, that a gear box like the US Gear unit would be less prone to have problems in the long term.
Let me suggest that maybe if a number of us wrote the US Gear customer service group and expressed a desire to obtain one of their units for our trucks that they might sit up and take notice.
One thing for sure, none of the Overdrive units are cheap and the payback takes a long time. I'd just like to reduce my RPM's when I'm on the Interstate rather than run the crap out of the engine. Lektrikman