Is there something that I can do to the allison tranny that can be tapped into that can eliminate 5th gear(when needed) like the 8th mile? So that the tranny will stay in 4th gear until "I" tell it to?

Thanks,
Mikey

O/d lockout switch from kennedy diesel or gm

GM has the switch. I did it on my 01.

I did mine with efi live and I did it for a buddies truck as well.