can someone help me id this

 

To control brake lights?

 

Go old school and unplug it and see what doesn't work...I am thinking rear brake/run/turn module.

 

Looks to me like an electronic fuel adjuster for fuel injection (like a Dobeck type unit).

 

I agree. What brand it is is another matter! As your bike is a dresser I suggest you post again in the Touring section, where there are plenty of chaps with experience of bikes from that era. Hopefully they will solve the query in a jiffy!

 

It appears the mystery box no longer has it's label, but the adhesive remains. Check the back side for either molded or stamped part numbers and run a google search. If no joy, then go old school and chase the wires. Where does it plug into? More than likely, the colored wires on your mystery box should correspond to the bike's factory wires. If not, check the the wiring on the factory side for colors and bounce that against the wiring diagram in your FSM.