These are keyed to the trunk key. I got lucky when I found mine in a wrecking yard. I took it to a locksmith and he had it repinned to my key in a day. I haven't seen any since, except on eBay.
They were also available from the Ford dealer parts department, which obviously would not be keyed the same as the trunk key. If you do search for a lock, one other thing I have found out is that the 65 and 66 (also 65 with pony interior) are different. These locks were being remade in the early 90's by a comany in New York, so some vendors might still have them.
I have heard that the "snout" on the 65 WILL work on a 66, but is is about 1/2 an inche too short, so it looks kind of goofy.
I'm trying to find one as I'm tired of people opening my glove box at car shows. (My stereo is in my glove box, so they don't need to be poking around with that. . . . )
I've looked around and haven't had any luck yet. . . .
I don't mind having it rekeyed--that isn't a problem. The hard part is finding one!