Version 1. Solid gun armoured cover.
Pz.Kpfw.III Ausf.N, Pz.Kpfw.IV Ausf. A, C, D, E, F1, StuG III Ausf. A, B, C, D, E
This is partial text from the full article (usually with photos) at https://armorama.com/news/7-5-cm-kwk-l-24-barrel-75-mm-m3-l-37-5-barrel