2003/04 ECM in a 2005 Excursion ?

[Jeremy]

This may help a little

Using a F-series PCM in a EX - PowerStrokeNation

You shouldn't have a problem having Bill reprogram your pcm, but I would try to find a pcm from a 04 truck(a true 04/04, they're were 03 engines in early 04's) use that in your truck and ship the EX pcm to Bill for reprogramming. I only recommend that because the original pcm will have all the PATS info in it Bill will need to program into the pcm when he rolls it back. He may be able to do it remotely for you aswell, but excursions add a little more difficulty in having the PATS data stored in the pcm. And he'll need that info if you want your anti-theft to function correctly. If you don't care then use the truck PCM but you'll have a theft light flashing for a little while at each start up as described in my post above.