Like Casey said, you're looking at around 7000lbs curb weight, which is the actual wight of the truck. If it helps, I weighed my 03 V10 Superduty V10 ext cab, short bed and it came in as 6900lbs one time and 6800lbs the other.

Since the diesel wieghs about 500lbs than the V10 engine yours is probably around 7300lbs with a 1/2 tank of fuel.

Also agree with Casey: Your state is not licensing based on actual curb weight, but the gross vehicle weight rating (GVWR). The GVWR for 99 to 2004 F250s like yours was 8800lbs. According to the new Ford data, the 2005 GVWR for your truck is different.

Ford now lists GVWR for 4x4 F250s at 9000 to 10000lbs depending on the transmission and gears I guess. In any case, it's now over 9000lbs for the 2005 models so I'd say your dealer is right any you'll need the "D" plates.