Triumph 908ML cord assembly is printed on mine. I'd a sent it along, but my voltmeter is grafted into it.
On a Speedmaster, the tach wiring harness will plug into the 3 wire brown, purple, and red w/ blue stripe socket
And also into a two wire red and green w/ red stripe socket, which looks like you have both open in the photo
If you do a search for who replaced tachs with an aftermarket model around here, you might find a spare harness kicking around somewhere. Chances are it's going to be a dealer item. Libby's in New Haven has done well getting me odd Triumph parts, and will mail them.
http://libbysmotoworld.com/
