Jeff.
Tell them that they are not "wrong", but that the book has incorrect data.
Then explain that the problem stems from the Spaniards at GasGas who always felt that they knew a better way of doing things; only coming around in 2002, when they used a "C" for the tenth digit to denote that that was a 2002 model, and each subsequent year had a successive letter, making your 2005 have an "E" for a tenth digit.
If that doesn't work, then ...
Maybe print out a post from the forum that says this.
or
Maybe they would accept a statement from a dealer as the proof they need.
I'll write you a letter, if they will accept something from a former dealer.
Good Luck and Good Riding!
Jim
.