The photo above was taken from the Army Transportation Museum at Fort Eustis, Virginia.  The guntruck concept was born in Vietnam in an effort to provide protection to convoys.  Most of the guntrucks where built out of 2.5 or 5 ton 6x6 tucks, but Otto II obviously was a M37.

The actual caption from the Museum's Portraits of Guntrucks in Vietnam on their webpage is:

"Otto II," named for the Beetle Bailey comic strip, is
most likely the second build for this truck. The
soldiers are unidentified, and the unit unknown.

I'm sure the Museum, as well as I, would love to have more information on this.

The "Other" Vietnam M37 Guntruck

I don't have any information about this guntruck, or the guys whom I think are the actual subject of the photo.  As with OttoII above, I would love to hear any information that anyone has about this truck (or the guys...).