What I've read is my 4.6L tensioner should only require a 1/2" breaker bar. Maybe my '04 just has a bit of corrosion on it, but it didn't fit and I didn't wish to force it (we all know what happens when we do).

If it's supposed to be 1/2", I'l grab my Dremel and clean it up a bit. If not, what size is it?

 

It is a 1/2" drive.