I replaced the relays in the control box several years ago as a precaution or preventive maintenance issue due to the age of my coach. It uses the same relays as those that are use everywhere else in my coach, but I can't recall the identifying number. I had bought a box of 24 on e-bay a few years earlier, so the cost was minimum to me. The box is black, about 5 inches square, and has Allison written on the cover. Mine was in the ceiling of my electrical bay, and right under the touch pad.
A second potential problem is one of the main relays could be sticking. The relays look just like those used for starters in cars in the 50's and early 60's, and look like a miniature beer can. They have copper posts in each side and two smaller electrical connections in front. They don't last forever but will generally fail intermittently, so there is some warning. If the relay doesn't work, your transmission won't be activated.
Good luck.
Holiday Rambler Navigator DP, Hummer, and Honda VT1100C Shadow