Good Day!
I'm looking for Sprue "U" which has just one item on it, the hump on the nose that is specific to late AV-8Bs in USMC service. It was included in the "Night attack" and "Black Sheep" boxings.
The easiest would probably be if you have the "Black Sheep" boxing, and decided to build the radar equipped B+ option, as it would then be extra.
Cheers, and thanks!
Hoops