I saw 'Mail Call' a few days ago on TV and it featured the armor museum at Fort Knoxx. There was a tracked vehicle I believe was used by the US Marines that had three long barrels/tubes on each side and parellel to the vehicle. each of the three barrels were separate from each other by perhaps a foot. I don't know if they were rocket tubes or small cannons because I missed that segment of the show. There were no other weapons on the vehicle that I could see, but themn again I caught only a few seconds of it. I don't know what period it was built but I would say somewhere between the fifties and seventies. Can anyone identify it?