This is a USMC D-9 dozer and it is one of three that saved the lives of some men in 1/61.
One of the 1/61 rifle companies was conducting operations near Wonder Beach early in 1969. On the way to an ambush site one of the 113s slid off a bridge embankment and overturned. Several troopers were pinned under the track. The USMC dozers were working in the area and their drivers volunteered to drive to the accident site and help. They did and with their big blades were able to lift the M 113 and free the trapped soldiers. Broken bones and lots of bruises but no one lost.
Thanks Marines.