Märklin produced the German class 23 mixed traffic loco from 1954 to 1972, during this time there exists 9 variants including both plastic and die-cast body versions. The body on mine is from 1954 and the chassis is from 1956. Below I have included pictures of the plastic and die-cast bodies (the die-cast variant is closest the camera and was issued in 1956 only).
Br 23 is a lovely runner and has had several spare parts to get it back into form. Seen often at Harrow Park station.