Thank you for that hint. But basically it was an academic question, on which type of plate belongs there, but all hints direct to the wide type.
The fact alone that I found a solo plate of the wide type at the same place I found the camera lacking its plate and that the plate fits only losely is a hint that the camerea come with that one.
About the reason I got no idea. The spring plate is stamped, thus got a fixed lenght. There seems to be no mis-bending either. The studs at the back are most likely fixed by means of a gauge, thus of standard positions too.
Anyway, as even at changing films the plate is likely to fall out, I shall glue one side of the spring plate in central position with hot-melt to the back. By this there is no chance of it falling out and still there is enough lateral play at compression.
Ordering anything is out of question as I just lost an internationa parcel within Germany after passing customs and DHL is completely unresponsive. (First time I have had something sent from abroad for over 15 years, prior shipments were utmost troublesome at DHL too...)