Quite a few old sites still exist in Da Nang. Most are overgrown with brush, of have been converted to Vietnamese military facilities. There is an old Air Force/Army communication site located about half way up Monkey Mountain that is still relatively intact. There are still two huge "Tropo" billboard radio antennas standing that were part of a comm link to Pleiku. You can drive by the site and take a peek, but dont go wandering inside the compound as its used by a Viet Telecom company as a Cell tower site.
At the top of the mountain you can find an old Helo pad and what remains of a HAWK SAM missile battery site. The Vietnamese have placed a sign at the entrance describing it as an "American Air Base" even though its only several acres in size. Also near the top is the old Marines MACS (and AF) Air Control radar site which is now being actively used by the Vietnamese.