I have seen people say the have and just need new valve covers, and i've seen that you can't................ so what's the REAL story?????

 

Yes, you can put PI heads on either a 4.6 or 5.4 windsor motor. From mid 1999 and up they started putting in the PI heads. My 2000 5.4 windsor (manufactured in december of 1999) came with PI heads.

As for installing them, i'm pretty sure they bolt right up. Even the valve covers should be the same (not 100% sure though), but i think the only difference in the heads is the intake ports and intake manifold. So you're going to need a new intake manifold for the PI heads.

 

Yep, you can swap heads off of all the blocks. You could even go as far as to swap a 99 5.4 PI head onto a 4.6. And for further reference, 4.6's didn't get PI heads until 2001, while the 5.4 was lucky enough to get them in 99.

 

the valve cover issue was only because the romeo valve covers had 11 bolts and the windsor had 14.

 

Helloooo, 2009!
This trivia took hours and JBrew to locate, so I wanted to save it where it might be found.

The aluminum manifold was made for the 5.4 only 1999. In addition, mid 1999 was said. My Windsor was dated 5-1999. I was sweating it. The paper label was still on mine, on the driver's side of the block. ~"Ohh, CAAaaNaDa, Oh Canada..." (Just a lil fun. Feeling V happy after inspection my donor engine.)

LOOK on the passenger side head's outboard side, near the front, for "PI," under a few other numbers. Not all 5.4's apparently have this mark, but if you see it, you are golden, in that regard.