That's one of the instrument light connectors (to add auxiliary lighting). I'm sure I have a few, if it's this exact same triple female connector you're after and not the blue with red male bullets, which might be a bit harder to dig up. On Ebay I'm sure I could sell one for $19.99 plus $22.17 in shipping, but if you PM me with an address I'll dig one up and mail it down/up/over to you.