Transynd is the fluid recommended by Allison but if you go to the Allison website they will give you a listing of other brands that are also TES-295 approved. As long as you use a transmission fluid that is TES-295 approved you are good to go. DO NOT let some auto parts guy in to telling you that their fluid is just as good and will work. If it does not state that it is TES-295 approved on the label, do not use it. NAPA should have what you need. It is not real cheap but it is what you need.
Allison fluids