Both of my 2003's have the snowplow prep package. However, I don't think you can get the plow prep on every truck configuration.
As far as what the prep package gets you is another story. The CTD has the smaller 136 amp alternator no matter what package you get and the "as advertised" 160 amp alt is reserved for gas engines. On the other hand I do belive you get different front springs because I did a comparison between my 2500 Q/C with another guys comparably equipped 2500 Q/C who DID NOT have the plow prep and my truck had different front springs than his. Also, My regular cab has the same front springs as my Q/C did.
If you DO NOT have the plow prep on your truck and damage occurs D/C can refuse warranty work if the damage could be related to plowing.
Blakers, I needed to get a new wiring harness and sub frame when I switched my 8' Fisher from my '01 2500 to the 2003.
FYI There is no plow prep for 1500's.
Hope this helps.