P-38s could actually carry much bigger DTs than we have to, up to 300 gallons. Occasionally would see a 300 gallon tank and a 1,000 or 2,000 pound bomb for long range strikes.
I think they could carry either the small 75 gallon, 150, or 300 gallon tanks, but I'm not positive.
Incidentally the P-47s used in the Pacific frequently carried the lockheed-designed droptanks with the tapered tail, they were a near perfect fit.