That is a drop tank.
Greebo posted about a new skin for a P-47M "Lil Snokey".I looked up the Pilot and found this photo.http://www.littlefriends.co.uk/gallery.php?Group=355&Style=searchItem&Item=119&searchString=robert%20s.%20johnsonIs that a bomb loaded on the plane or a long, slender drop tank?
I am not 100% sure, but I think that was refered to as a "dam" buster, 2,000 lb bomb, used in Italy for bridge destruction. If you will look up operations of 57th fighter group, they talk about this bomb and how they were used on bridges. Italy had more bridges per square mile than any other theater of operations for U.S. forces. I would guess that Russia has the most!
Nice Randy. Notice the P-38 was the longest ranged and a P-51 with no tanks (and I presume no fuselage tank) wasn't much longer ranged than a Spitfire.