Thanks for the connector info Bob. Was able to locate locally at Mouser. (catalog page)
I happened to find an unused one in an old computer in the mean time but my main controller is a little different from the 3020, the spindle controller is the same though.

Now I have to trace the signalling on the controller. Which control on Mach3 can I use to turn the spindle ON/OFF without running a program?

Louie