I'll get it straight for yuh, well what I can anyway, -
Here's a little more about the head upgrade,-
A friend from another sites quote, about the heads (03/27/2010), -
"Here's the info I have from Ford brew. I can't verify this at all so take it as you will.
Supposedlly any heads manufactured after November 12, 2002 were redesigned 8-thread heads
Seeing as Ford builds lots of parts ahead (see what I did there?) of time, early build 03 trucks got "old stock" heads and engines.
Note, I'm talking about the build date of the heads and engine here, not the build date of the truck.
Casting Numbers you say? Look on your driver side head and look for
Individual Part No's for the 8 thread heads are.......
Right some model years did have an intake gasket leak problem. The problems will not happen IF you purchase Intake Gaskets from Ford only. They were able to customize their gaskets to take care of the problem. You had to get from Ford, not sure if it's still that way but changed the gaskets just about every other year, along with the location pins on the gaskets. So gaskets are model year specific, - many are thicker one side than the other or thicker just in certain areas. It's sort of old news now, but when fishing for intake gaskets, get them from Ford. That way you get the latest revision for your model year.
Let see what-else
Nope, The 5.4L PI engines intakes are ALL plastic except for 1999. The 4.6L's is a different story.
A BIG problem plagued the plastic intakes. They would crack just under the passenger side crossover. Right at the flange. Once that eventually happened and you can just about count on it, - the ONLY fix was a new intake...not cheap. The best intakes were the 99's, - You can Port Polish gasket match that intake and it will last for ever.
But, hang-on. Ford did something about this and the new intake went into the 03 models. What they did is improve the composit material and made it stronger. ONLY the 03's have these intakes.
If I had a choice I'd run the 03. It's already smooth...polished and so far they've been holding up.
Plugs: Nonono lol, do not run ANY Autolite plugs in these engines. You mean, you actually got away with running them in your 98? Your a lucky man. AP/APP 103's and 104's are about the worst plugs fro these modular's. Incorrect heat range. If they fire at all, it's not for long. Bad economy , bad performance, short life. The only plug that worse than those are the Bosch plugs. Bosch plugs eventually fall apart in the cylinders before they start missing. Use just these in that engine, -
Build date is on the heads. If it's a reman, they are metal tagged front or rear of the block. Build date for the truck is inside the drivers door.
COP's - Only these, Motorcraft DG508's or Visteon 60-1000's (DG508's). These are the ONLY coils built to Ford spec.
Did you know, - if you thro that 03 top end on that 98 block, you'll net more HP and Torque than you would with that 03 block?