"From what I gather, both variants use an A2 turret. The difference is that the jarhead version (HC) has an electro-optical jammer installed in the, for lack of better term, hole where the CITV would be mounted on the turret roofs of the Army HAs. The A1 HA has a cover plate bolted over that hole."
The turret on both the US Army M1A1 HA/HC/AIM and the USMC M1A1 HC/AIM are the same and all are M1A1 turrets with the manhole cover bolted over the opening where the CITV is installed on the M1A2. The manhole cover was introduced in M1A1s in anticipation of a later variant with the CITV. The USMC HC/AIM simply has the mounting strips for the MDC bolted on top of the manhole cover.
Gino P. Quintiliani
Field Artillery --- The KING of BATTLE!!!