G and H model P-38's are lighter than the J and L models, and the H model has nearly as much power.
The H and earlier models had no outer wing tanks at all, the area that the J and L use for 55 gallon outer wing tanks is occupied by the intercoolers on the earlier model birds.
The H and earlier models also did not have power assisted ailerons. This means that the controls will become heavier at high speed and it will resist input to roll. There should be little or no change in the elevator and rudder feel. On the other hand, realize that the P-38 had a yoke and wheel, so you could use both hands to force a roll, and when combined with rudder input it rolled okay. This is only a concern at high speed. At low speed there's not the resistance to roll that there is at high speed.
The G and H models are what the 20th and 55th FG's went to war with in late 1943.
Also note that WEP time may be reduced, because without the more efficient intercoolers and oil coolers, the earlier models got hot faster.
The F and early G models would belong in the early war group, and saw action in the Med (including North Africa and over Italy and Romania) and Pacific mostly. The late G, H and even the eraly J models would be mid to late war.
The early J model would actually be considered mid war plane and a somewhat early model P-38, since even the J was not the final evolutionary model. The J models had several versions, unlike both the H and L.
