Back in 1998 it took a US ETO Ordnance Technical Intelligence Report to let me believe this story.
Rumors of a cargo variant were numerous. The last version of the Sd.Kfz. 11 has an armored front, so there could be an easy confusion.
The concept stirred not only my imagination, conversion drawings, and even a model of a 251 cargo version have been seen.
The real thing exist, but is a little different.
Dated February 11th 1945 a technical intelligence report shows a captured example by the 3th US army.
It looks like a 251 /17 with the cargo bed but a trip book dated November 24th 1944 names it Sd.Kfz. 11/1.
That number was assigned previously to a smoke generator vehicle on the unarmored 3 ton chassis. The registration WL-563120 places it in the Luftwaffe. The nose is the same as the standard 251, except for the MG mount, that lacks. The rear two-third of the bed is not armored and a portion of the sides hinges down to facilitate the loading. In the back of the driving compartment there is a guard that serves as a front wall for the bed, to protect the crew from shifting loads. Three pressed steel hinging sheets attached to the sides and the floor.