I probably shouldn't say this before I know for sure but I'm gonna say you can probably upgrade the bow with a 2003 cam. Just so you know though, BowTech doesn't sell cams outright.
If the 2003 cam will work (and I don't see why they wouldn't) the owner would have to pay XXXX dollars for the new cam and return their old cam in an exchange.
They will only make these transactions through Authorized BowTech Dealers.

I'm guessing the string and cable lengths would be the same for each cam...