When I showed the photos of German SPG's to Vladimir Matveevish, and asked him to pick out the "Ferdinand" he destroyed, he
pointed to Hetzer.

Hetzer	Jagdpanzer IV

However, Germans started producing Hetzer in the second half of '44, and so there weren't any in Ukraine in March. In that
case it is logical to suppose, that the SPG destroyed by the Malyshev-Zimakov team was Jagdpanzer IV. Unfortunately, I did
not have its picture at the moment, but its silhouette resembles Hetzer, and besides, it was produced starting January '44.

Thanks to AMX for the info.