Reverse indicator light

When I purchased this Duster, it came with a rallye dash (which I plan to install), and also a reverse light that fits at the lower dash, as I am sure you are aware of. However, it didn't include the bulb socket and wires. There's just a small shaft with threads and a locking nut. Does anybody know where I could locate one of these bulb sockets? I was hoping to install this along with the dash.

Thanks!