In an attempt to make a competing touring derailleur with Shimano and Suntour, Simplex made this kinda hunky & heavy Long caged rear derailleur, the SX-610. I believe this can take 6-7 speeds, and a maximum cog of 36t according to sutherland's 6th edition. Made in and around 1982. Don't try to make sense of this thing, its french. 

Pulley bearings are mint & they spin freely.