In my opinion one of the major flaws in USF design is there tech scheme. Which costs as much as other factions to arrive at medium tanks but leaves them missing key units and also I feel like causes units like the Stuart to have to be balanced to arrive near the same time as the other USF light vehicles.
I propose these:
LT teir becomes a requirement for Captain tier. So that USF must tech LT -> Cpt -> major
Cpt ans LT side tech to unlock units removed and price rolled into tech cost of the building
57mm ATG added to LT and removed from Cpt.
M5 Stuart moved from LT to Cpt.
M5 Stuart -20 fuel Cost.
Major tier reduce cost so that it still takes 205 fuel to reach after going LT and Cpt.
This gives USF access to both team weapons early in the game, puts a natural delay on m5 stuart and pack howitzer and prevents USF from needing a back tech to unlock all team weapons.