One of the variants of the Panzer IV chassis was the tank destroyer version known as the Jagdpanzer. Initially armed with a short-barreled L/48 7.5cm gun, it was decided in 1944 that it should be up-armed with the long barreled L/70 7.5cm gun whose increased muzzle velocity was believed would be a more effective anti-armor weapon. However, production and refits could not keep up with demand and it was decided that an interim solution was needed - this would be the Alkett version. Alkett was the manufacturer of the venerable StuG and production of this version would be produced in their factories through the simple expedient of welding a large casemate structure unto the Panzer IV chassis. This resulted in an odd, high silhouetted tank hunter that was ungainly and (likely) not very successful in the field, with under 300 produced. Unfortunately, no one makes this version in 1/56, so I set out to convert it myself.
More pics and info:
https://empireofghosts.blogspot.com/2018/11/jagdpanzer-iv-l70-alkett-conversion.html