you Said the leak is on the front of the truck (right)?
Allison trans line are known to fail. there are a couple of aftermarket fixes. I used an aftermarket kit to replace all three hoses on my 2006 truck. about $200 and two hours of work. the hoses weren't leaking real bad but the fluid would collect on the plastic skid plate on the front of the truck and then start to drip. most of it was leaking just behind radiator on the passenger side.
I also had a leak where the yoke slides into the transfer case. it flung trans fluid all over the place. that was a cheap fix also ($10). never pulled trans or spent much money. been dry for over a year.
