Originally Posted by ZeroTX
Sounds like someone knew about this and patched it up enough to sell it to you. No idea how it didn't fly out. I'll bet they were praying it wouldn't blow out on the test drive.
The method above is what people usually say to do. It sucks to have to do it. I am putting a 2009 4.6L 2v (Crown Vic) motor in mine and I'm hopeful that maybe the 2009's have more threads on the heads.
The only thing I know for sure is '04 4V heads have more threads than '03 4v heads.
Take a look at the link I provided. There are Lock N Stitch thread kits for all kinds of Ford heads. They come in different diameters and lengths suggesting some 2V heads have more threads than others. Maybe the company can tell you if your '09 heads have more threads than earlier versions.
Then again, you can just take a plug out of your replacement engine and count how many turns it takes to seat it.