Flakpanzer IV Ostwind

The Flakpanzer IV Ostwind or abbreviated Ostwind Flak Pz.Wg IV was a self-propelled anti-aircraft gun based on the Panzer IV. It was developed in 1944 as a replacement to the earlier Flakpanzer IV Wirbelwind.

The Panzer IV's turret was removed and replaced with an open top, hexagonal turret which housed a 3.7 cm FlaK 43. As well its intended role as an anti-aircraft weapon, the fast firing gun was extremely effective against light vehicles and minor fortifications. A closed top design would have been preferred, but this was not possible due to the heavy smoke generated by the gun.

The Flakpanzer IV Ostwind's main improvement over the Wirbelwind was the 3.7 cm FlaK 43's increased range and stopping power over the 2 cm Flakvierling 38 and slightly better armoring on its turret.

While an order for 100 vehicles was placed in August 1944, only 44 vehicles were completed, 37 converted from existing Panzer IV's and 7 new production vehicles from December 1944 to March 1945, all work being carried out by OstbauWerke in Sagan, Silesia.
http://www.wehrmacht-history.com/heer/anti-aircraft-vehicles/ostwind.htm