The toy-sized Katyushas were used in small scale street
fighting...
A German 88mm gun mounted on a 150mm howitzer chassis. A
war trophy from the Leningrad Front
"88-mm Germanskaya protivotankovaya pushka obr. 43/41".
Or, in English, the PaK 43/41 88mm ATG.
and here is the proof !
This gun is the later L71 PaK version, that went into the Elefant,
Nashorn, Jagdpanther and Tiger II. There are two mountings for this gun,
the "traditional" cruciform principle one (called 'Barndoor')
and this, the second version, a stop-gap measure to get more guns into
production. It uses the same gun, but the carriage from the German 150mm
howitzer. This is a standard version, not a one
off experiment.
A Big Thanks to Alex Oldenburger for
translating and adding the background information !