Hi Bob,
I think I can help you. I bought an 06 Kestrel for my 06 Tundra and had to add about 2.5 inches to the bottom so that it would fit the height of my truck bed. No big deal. I did learn however, that the 00 to 04 Tundras have a shorter truck bed sidewall ht than the 05-06 models. The Kestrel fits the 00-04 Tundras as is, the Hawk will fit the 05-06 models just right. You can put a Hawk on an 00-04 Tundra but it will ride about 2-3 inches higher than ideal in the bed. Should still work IMO if you mount it securely.
Good luck,
Eric