From a purely game stand point, I would like twin 75 gallon drop tanks. These may have been used in the early part of the war for P-38s. Not sure about that.
The lack of symmetry of a single drop tank bothers me for no good reason.
A lot of people are not going to understand this explanation, but knowing you like to know the "nuts" and "bolts" of things, here is something I was told!
You have to remember that these 38's were operating off of un prepared fields of minimum length at best in some cases! The most important "speed" in any twin engine aircraft is the "minimum control speed on one engine"! If you are less than the minimum control speed and lose one engine, you are going to crash if it happens right after takeoff. Yes, the 38 had counter rotating props to counter act the effects of torque and "P" factor, but had no effect on VMC. The "off set" big drop tank added more danger to the pilot when installed! According to some of the manuals I have read on it, if you lose the right engine below VMC, the effect of drag the drop tank produced means nothing because you are going to die anyway! On one engine, below VMC, the aircraft is going to roll over and because of the "moment" arm of the engines, its going to nose down and then, a big fireball, with you as the "marshmallow"!
The effect of the drop tank is that it raises the VMC 8 to 10 knots, depending on which engine quits!