The writing on the reverse comments on crossing the Bug. The sign on the right "Grenze" reminded me of a an image in my "as yet unknown" pile.
Apparently "Grenze" is not a place name but means Border. There are a couple of similar image of this column of PzIVs which show the vehicles carrying different styles of non-standard turret bins. So potentially there is a match up here with; no known images of 16th PzDiv PzIVs from behind in either 4th or 8th K, these unaccounted for images and the location in the first PzIII image.