The spindle encoder requires 5VDC and has two outputs: 1ppr and 150ppr. (ppr = pulses per revolution).
For threading in Mach, we can use the 1ppr signal alone; the 360ppr signal isn't required.
The connector on the end of the encoder cable is an AMP 206434-1. The chassis-mount connector it mates up to is a 206433-1. You will also need four pieces 66569-3 solder cup female socket pins. Or just cut the connector off -- the wire colours are listed.
If you know of other machines this encoder is present on, please add them to the category list below.