* Custom Deluxe/Sierra - base model
   * Scottsdale/Sierra Grande - cloth seats and chrome trim
   * Cheyenne/High Sierra - more sound deadening and chrome
   * Silverado/Sierra Classic - wood interior accents, carpeting,
and more chrome

For instance, my Blazer was a Police truck, so it's really 'no
frills'...it's a Custom Deluxe.  Vinyl seat covers, rubber floor mat,
no interior trim panels in the back, am/fm radio with no tape deck,
single mono speaker in the center of the dash, etc...

1500 means it's a 1/2 ton truck, whereas 2500 is a 3/4 ton and 3500 is
a 1 ton.  Previously, they used a different numbering system (10, 20,
30) to represent the same three variations.

The Wikipedia article is pretty good:
http://en.wikipedia.org/wiki/Chevrolet_C/K

~jp

Also, this is specifically talking about Blazers, but the info applies
to the other trucks as well...

http://slosh.com/cars/blazer.html

~jp

Its like Biscayne, Belair, Caprice, Impala. they were all the same car,
but each one had a little more than the next. someone saying Silverado
Cheyenne
is blowing smoke, or just doesn't know.  Currently Silverado is the 'loaded"
truck. The Cheyenne was a mid model, between those two was the Cheyenne
Super.   Below the Cheyenne where the base models, the Custom,  and then the
Custom Deluxe, these two where what most fleets bought.   And above all of
them was the Scottsdale, but I don't think that designation has been used in
a while.
Mechanically they are the same, same frame, drive train etc. so the
Silverado would have power windows standard, where it would be an special
order option on the Cheyenne.

Whitelightning