Cadillac Gage V something or other ? or some trials test bed/prototype . Pretty gawky looking rig and makes me glad (sorta) that the CF went with the AVGP family of vehicles.
OK, I got it, it is the MAC1/MEX 1 a private venture by Chrysler in the late 60s.
http://www.military-today.com/apc/mac_1.htm