I think all you need is the newer oil rails and stand pipes, valve cover, and oil pump cover from the 05. I never really just set the 2 side by side and looked but I think the rocker box will bolt to either.
So if I wanted to put 03 heads on my 05, technically nothing changes? Just use all my stock 05 parts. I wasn't sure if old style oil rails had a different bolt pattern or something along those lines.
The stand pipes off a late model won't work on an early model, you will have to swap over the rocker boxes and use the early style oil rail and fittings. The early style rails are better anyways. And like someone said you'll need stepped dowels.
Wait....are you working on an 03 or an 05 truck? Either way you will need to swap rocker boxes and use whatever oil rail you had in the first place. The heads themselves are identical other than dowel size.
There are 3 different rocker box configurations. You had 2 styles on a 18mm head. Stc style log rail and newer web rail with torx bolts. The upper bolt holes and dowels are smaller than the 20mm style web oil rail with torx bolts.
I did not realize these differences until I have got into swapping 20mm heads and new hpo system onto an 03 engine. And from what I have seen ford used 18mm heads with the new hpo system up until 06.
He's only swapping the heads onto his 05, not all the other stuff. You should be fine, as long as your truck hasn't had the heads replaced by the ford dealer. 18mm were on 03 - early build 06. All 18mm heads are the same.