This is going to be the Ontos Armoured Recoiless Rifile Carrier.Ontos in Greek means "Thing".It had 6 106mm Recoiless Rifiles and one 50 calibure machine gun.It had great firepower but the backblast of the Recoiless Rifiles gave away where you were hideing.It was used for a while in Vietnam.

                                                     JOCOOL. 8)

Link about the Ontos:http://ontos.homestead.com/main.html