Looking through some models recently and I came across the following difference between two of my BMW's. It appears that there is a cylindrical shape on the inside of the roof.
Anyone seen it before ? is it just a manufacturing error ?
Yes that is correct. When the model was first launched in 1976 it had a simple window section with a smooth upper part. In 1977 they created a Polizei casting for the German market, which involved a modified body with a hole and a separate light dome. to work correctly they needed a bed to hold the dome in place so modified the window section to have a lower disk that the small dome unit could slot into, held in place between body and window. Once the window section was modified they just used that modified part regardless of whether the dome body was being used or regular body. So you will find no lower circle places production as 1976-early 1977. With lower circle places production as later 1977-end of production (1981 for orange bodies and the red bodied 1982 giftset version).