The M35A3 is also an M44 variant, in fact I have seen one recently listed AS an M44. My own wild speculation is that the M35A2, M109A3 and M185A3 vehicles are specifically being purchased by an entity with deep pockets to be parted out for the purposes of spare parts resale OR more likely to have a spares inventory for maintaining a large fleet of Deuces in a foreign country. That is the only way I can explain the 800 and 900 series 5tons and the M35A3 trucks being available when the others are not.
AGAIN, this is speculation on my part!
You expect too much logic from a huge government machine.
DEMIL code reviews go NSN by NSN, or NSN group by NSN group.
If the item manager for these trucks changes it, that change will only apply to those NSN's. The big machine only sees NSN's and DEMIL codes, and does not look for logic.
As an example- 3/4 ton trailer? DEMIL B/Q, EUC Required. 5KW generator? Demil B/Q, EUC required.
Trailer Mounted Air Conditioner Set, on a 3/4 Ton Trailer with a 5KW Generator? DEMIL A, no EUC required!
Why? The item manager for the AC sets said "there is no legitimate national security risk in an air conditioner" when he set up the DEMIL code. So when the DRMO/GL people set up the sale, they look at the NSN, look at the DEMIL code for that NSN, and sell based on that and that alone.
There is no deep conspiracy to sell the trucks to a single entity, and if there was it would have to be done in an open fashion. This is just the unthinking machine where somebody changed a keystroke in a computer from Q to F as part of a review, and everything else rolled downhill from there.
While the A3's are part of the same family, if they have a different item manager (I will look and see later) then a demil change for the A3's has to come from a different person in a different cubicle who is on a different schedule and may apply a different train of thought on the issue when/if they ever do change anything...