Hi CraneTruck!
Thanks for posting that picture!
Actually, that is a picture of this(my) truck during testing in Aberdeen.
My truck still has the Army assigned numbers visible and are the same as that on the one you pictured (see att.).
The only difference is that they have re-painted over all of the Kenworth Chrome/Stainless (which is beginning to show through - might clean it up and leave it chrome as original - an original MV w/ chrome! - not sure how that would work with camo???).
In your picture, if you look at the cutout at the cab end of the dropside bed (which is for the crane valve controls), the cutout has been elongated to the rear (up to the dropside gate) to make room for the pull-out manual outrigger supports. This change also seemed to require the changing of the boom to a slightly different HIAB boom.
The changes can just be made out if you compare the pics that I posted with yours.
As far as motorvation - it still runs the Detroit 6V53 (V-6) Turbocharged, Supercharged Diesel with an Allison 5speed Automatic.
As far as I can tell, this engine was in the military catalog used in mostly tracked vehicles (M113, M741, M125A1, etc.) but the Turbocharged version (6V53T) was only used in the M551 (Armored, Reconnaissance/Airborne Assault Vehicle, Full Tracked).
When the Army had Pacific make the XM977 (10-Ton 8x
they used the V-8 Version for the additional weight (8V92).
Tank to ya soon, Dave.