BMW R71 frame horn brackets, different types

[Topfmine]

I have notice on different BMW R71 frames that there seems to be two types of horn bracket welded to the frame which is also part of the seat and rear mudguard bracket. On one frame the bracket for the horn points down with a hole for the horn. The other bracket points down and back up like a small curl. Am i confusing these two frames with a R51 or R66.

[Luigi bmwR68]

If I remember correctly , on the hearly frames, without vertical reinforcement, the horn braket is straight, in the last 1941 frames it is curved as in post-war models (similar but not the same).
However the next days I will check.

[Topfmine]

Many thanks for your help, this solves many questions.