I finally broke down and drained the Dexron VI out of the Allison and switched to Transynd today.
Did the following method: drained the Dexron VI, filled with Transynd, drove truck for 30 minutes got tranny temp. up to 165 to 170 finally, drained that Transynd, changed the spin on filter, refilled with another 7.4 Quarts or so of Transynd.
Costed me a few bucks, but that is done and I should be good for a while.
The Dexron VI looked like new and had the original red color with no burnt smell. Truck had 47,918 miles on it and has not been worked hard at all. I think Allison reccomends changing the fluid at 50,000 miles for lite duty (correct me if I am wrong).