I found this column on eBay, and sent a message the guy who's selling it.
I asked whether the column included the flange on the end for attaching to a rag joint, and he confirmed that it does.
http://cgi.ebay.com/ebaymotors/ws/eBayI ... MEWAX%3AIT
I searched out the company online, and found a phone # and called him directly.
He rebuilds columns and sells them, and knows all about how hard these things are to find.
Then he mentioned that he 'might' have one lying around.
Long story short, he found it and sold it to me. I don't think he has any others at the moment.
If you're desperate for one, you could just buy that column with the flange attached... it is a very nice one.

'65 F100 Custom Cab Shortbed - current project
'69 F250 Ranger CS (Tug) - P/S, P/B, AC - 390/C6/D60 - Reef Aqua/Wimbledon White [sold]
'66 F100 Custom Cab (Shep) - 352/4sp/9" - Wimbledon White [gave to OldDawg]