Hello BobG
The striker on my 250SL is the same as yours (3 screws). The screws and the back plate were not chromed.
The striker itself is chromed. This disappeared on the later 280SL model.
I replaced one of mine with a good second hand one from a finnie sedan.
I am not sure when the change (3-4 screws) occurred.
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto