Photographed rarely, most known is a picture of a 251 /22 /D.
The duel engine-cover is replaced by a single hatch hinged at the rear. The filler cab for the radiator is omitted, and the front piece of the bonnet-armor gets hinges on the right side (looking from the front). The interior is unchanged with the exception of the wood replacing metal in the seats and bulkheads.
This 251 /21 "Drillig" is seen with its one piece hatch wide open, somewhere on the western front.