Vance had asked me to help identify the object seen below this B-24 in the general area of the ball turret.
It appears to be a Surface Radar dome … it would seem to correlate to the bto dome fitted in place of the sperry turret on certain late-block B-17Gs in the ETO. In the Air Force they called these Mickey" ships. This particular bird is painted in the Atlantic camoflage scheme of Dark Gull Grey over White is actually a U.S. Navy PB4Y-1, a navalised version of the B-24 used for sub hunting and the dome actually is an ASV radome for detecting U-boats. Another photo from the same flight appears in Bert Kinzey's B-24 Liberator in Detail, p. 46. In the sunshine the radome is an orange-tan color.
Additional images of the hardware ….
Belcher Bits 1/48 set BB-16 which includes the nose (Dumbo) radome and Leigh Light, also includes one of these belly radomes in a retracted position.