There are 30,000 reasons not to, of course-that's the dollar premium these companies charge over a conventional truck for either the Lincoln Blackwood or Cadillac Escalade EXT. But three years ago, the economy purring, it all made sense. Both companies wanted to make a statement. And in the Navigator and the Chevy Avalanche, both could borrow talent from the home team. There was no way to know that come 2002, 50 grand would seem a bit pricey for a spit-shined crew cab with a small, covered bed out back.