I purchased all of the parts out of a long defunct German auto repair shop in Santa Cruz, California, and this was part of it.  It's a fuel injection pump, with part number PES4M50/320R4/24 on plate on side.  It's been cleaned and disassembled and it's been this way since the 1980's.  IT COMES IN THREE PIECES; LOOK AT THE PHOTOS; IT'S NOT COMPLETE.  IT'S PARTS ONLY.