It's an "aileron rate sensor" and apparently it was a change they made with the Jetprops.
That 980 you're parting out doesn't happen to have Collins avionics, does it?
They think they've found one in "as removed" condition, so we'll see.
Of course, I'm always skeptical that this little box, after almost 40 years, happens to fail while the airplane is in maintenance... They did do the 900 hour autopilot check, so maybe it was disturbed or something.