I know this is a super old post, but I actually found the connector part number to do exactly what MAG00 wanted to accomplish. That was to keep everything as stock as possible and be "plug and play" from the tailgate to the third tail light harness. MOPAR makes a repair kit connector for doing this. The kit even comes with wires pre-crimped with the correct terminals. Just splice the repair wires to whatever harness you have leading to the third tail light. (this connector is for the third tail light harness female end, NOT the tailgate harness male end.)
I also originally wanted to do exactly what the others said... to use an old connector from an existing tail light and harvest the connector from that. As that would have been the best option. The original owner cut the tail light off and did not save the light. I am the third owner of this jeep and did not have the light to harvest from. Unfortunately after an extensive search within a six hour drive from my house, there were no tire carrier's or lights available in any junk yard, nor did anyone have one they would give up. Like jkx0778 said "NOT for sale". Everything on ebay turned out to be more expensive than the connector itself, so I just bought the repair kit connector. NOTE: The ultimate goal here was to keep the tailgate 100% stock "plug and play". Not to splice in a different type of connector or hardwire in something else.
These can be ordered directly from MOPAR Parts via Amazon.com. Use kit P/N: 68065023AA (it is a bit spendy at $30, but if that's the route you want to go, here it is.)