From what I understand the H model had the engines as the J but the same intercooler design as the G. The H also had a larger bomb capacity then than the G and the improved cannons of the J. Once they moved the the intercoolers to between the oil coolers as opposed to the leading edge of the wings, that birthed the J model giving it better performance then the H.
The differences IMO between the G & H or the H and J would be so subtle that it wouldn't warrant a good argument for adding it to the plane set. Now the F model I believe had less horsepower then the G and probably better stall characteristics and low level fighting capabilities then the G. I would guess that it'd be the better knife fighter of the lot , but would be harder to handle.
In all honesty though, I don't see them adding another 38 to the plane set as we already have the 3 main variants. The only 38 we don't have that would make the biggest impact is the K model, but that's not even an option as they only made 2 and those never seen any combat.
Now lets talk about the A36..........................
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