I discovered my alternator was a 2001 as was my camshaft sensor, WHY? on 2004 Ford Excursion

broke down, had part delivered 50 miles out, wrong part. Mechanic said it was an 01 part and most of my starter electrical probably is as well. I bought the 04 excursuin new, how can it have wrong parts and how is the owner supposed to know this?

Asked by for the 2004 Ford Excursion
If it were a second hand vehicle I would have guessed the engine had been swopped out.Look at the sticker on the door pillar/door jamb, look for the production date on the decal. Look under the hood at the emission decal it will say "emission equipment equipped for 2004 model year" if it is a 2004.