An extra piece of hardware

This piece of hardware is something that I thought would fit nicely into the two Heavy Weapons Companies of my 21st Panzer Grenader Regiment. Unfortunately, so far, I've not discovered any firm evidence that the 21st Panzer Heavy Weapons Companies had mortars. I do find this very strange that both battalions did not have any close support 81mm mortars, instead having 20mm Flak 38 and a Pak 40, and relying on the Reihwerfer of the 10th company for mortar support.

8cm schwerer Granatwerfer 34 auf Panzerspahwagen AMR 35(f)

Does anyone know if these half tracks were used in the Grenadier battalions of the 21st Panzer Division or which units they were used in?