Well I looked
Guess what, it snapped off
Not all is lost though, I am almost certain sure that Ford use a 1/8th NPT taper thread for temp senders ( More or less an industry standard )
I guess that's why most el-cheapo tap & die sets have a 1/8th NTP tap in them
Here's an ebay linky, not going to break the bank.
Ford Temp Sender