Dave,
Congratulations on noodling out a pretty complete maintence schedule. Here are some thoughts for you.
1. If your wheel bearing have not been serviced before, go ahead with it. It's time. You might consider having the hubs switched over to oil bath and they will be easier to service in the future.
2. Same with the coolant. If it's OEM it's time to chance.
3. If the Air filter is OEM it's time to replace. Cummins has recently recommended a 3 year interval for air filters as they can deteriorate from age and moisture.
4. You should have Transynd fluid in your Allison. The filters should be changed at 36 months and the fluid at 48 months. If you establish a schedule of fluid testing then you can change fluid based on the testing but the filters should be changed at 36 months.
Now that you've learned all this you might consider starting to do some of these items your self. Most of these items are doable yourself but I wouldn't attempt the wheel bearings.