These sold recently on eBay and were purchased by the Mechanized Military Museum at Camp Pendleton in San Diego.
Each unit will be restored and displayed at several museums.
excerpt from the original ad:
Here are four APU's, which stand for "auxillary power units". They were used by the Navy for aircraft support with their AC/DC PTO powered, onboard generators. On the APU's, instead of the transfer case shifting the vehicle into low range, it engages the generator. It's a pretty clever set-up.
The APU's are virtually identical from the dashboard forward as far as engine, trans, and transfer cases. The back end of these units have a tandem wheel setup (like the nose gear of an aircraft) in the middle that steers the vehicle in it's own length. The front wheels are fixed and are only used to power it forward or backward.
APU Jeeps in action: http://www.youtube.com/watch?v=xkXHBDty91A