Originally Posted by
T-Mar
In the event that my description was confusion, her's a picture of an SLJ5500, which should clarify the difference.
I've often suspected that there was some cross-licensing arrangement between Simplex and Shimano. The early Shimano derailleurs from the 1960s bear a striking resemblance to the Simplex derailleurs of that period, and the later Simplex derailleurs are equally similar to Shimano's later derailleurs.