I am sure the Terry Gander "Ian Allan does an Osprey style" book on the 250 mentions different shaped turrets on the armoured car version.
Yes, the SdKfz 250/9 had a different turret depending on whether it was the
Alte or
Neu version. This turret appeared on the
Neu version. It also appeared on other vehicles, including the SdKfz 234/1 and the Aufklärungspanzer 38(t) 2cm KwK38. From Rubicon's earlier post, they may be planning to use this turret for one of these vehicles (my guess is the
Neu version of the SdKfz 250/9).