T420 Thinkpad 1x1 upgrade options?

[siyan]

Stupidly, I ordered my T420 with just the stock Thinkpad BGN 1x1 hardware. Looking for an upgrade path but want to make sure I'm going the right way.

I looked under the DIMM panel and there only appear to be two antenna leads. One blue and one pinkish. I read various posts suggesting that every T420 was built with 3 antennas regardless, so maybe the 3rd lead is just hiding somewhere?
EDIT: Stupid me, thats the WWAN slot. I'll have to dig under the keyboard tomorrow.

If I get a 6300, can I just plug the two antennas and still get 2.4ghz/5ghz function?

Will the older 60Y3193 FRU work?

Should I just get a 6200 instead? (Also why is it that I can't find any Lenovo branded 6205s on ebay, only 6200?)

Thanks

PS: as a point of curiosity, where is the antenna for the existing built in Thinkpad 1x1? Is that where the 3rd one is plugged?