The late Russ Dugger was pretty sure this was the site of the old gap-filler annex, and historic aerial images from the USGS have confirmed this. Nothing to see there now, though.
Looking North
Looking East
Looking South
Looking West
July 2004 photos contributed by Tom Page
The photo shows the location of the former gap-filler radar site at Parris Island MCAS. According to historic USGS aerial imagery, the facility was in this now-empty field, near its center. No traces of the radar annex remain. [looking east-southeast]