Mike,
I hope this isn't too late. I also hope your problem is the same leak that I have.
My US Gear overdrive is leaking at the gasket where it mounts to the transmission. This is just a regular paper gasket that came with the kit. When I get around to it (probably sometime this winter) I'll drop everything and use RTV silicone sealant to replace that gasket. I've had better luck with silicone sealant than with paper gaskets.
The US Gear overdrive doesn't have oil seals on the shafts at each end. The only thing that encloses the oil are the gaskets between the overdrive unit and the truck's transmission and transfer case.
If yours is leaking from the same place, then any half-way competent mechanic should be able to fix it. You don't say whether your truck is a 4x4 or 4x2, but the fix would only involve removing the driveshaft(s), transfer case (if installed), and US Gear unit. Clean the surfaces, apply the RTV material and reinstall everything. Don't forget to refill the transmission.
I like to wait about 24 hours before filling my differentials when I use RTV sealant, but you may not have time for this. I haven't checked, but I understand that Dodge dealers sell an RTV sealant that cures faster and can be used immediately.
Good luck,
Loren