Jackson is very strong, but the USF has no choice but Jackson
If Jackson is nerfed, the USF faction itself can fall
So we need to give the USF new options and nerf Jackson
...
This is a just hypothesis, so one can simply nerf the M36 especially its 60 range performance and see what happens.
The majority of USF doctrinal units are excellent but they see little action and a contributing factor is because the M4A3 Sherman+M36 combo is simply too cost efficient.
105mm Bulldozer Sherman (380/140) is at least as cost efficient if not more than the more expensive Brumbar (400/150)
M4A3 dozer upgraded (390/130), M4A3(76) Sherman (380/125), Sherman Easy8 (380/140) are all more cost efficient than Ostheer PzIV J (380/140)
And the M10 is great with abilities available to it.
USF vehicles hardly need any buffs.
If there is Ostheer T3 units become too dominant vs USF and that is a big if, other option should explored.
That is why I suggested making the stock Sherman better vs PvIV (while removing the HE to open the way for doctrinal units) and nerfing M36 vs PzIV.