the only commercial [truck] codes I've ever seen for the standard factory colors in the TF years are 200, 500, and 700 series numbers - you may have one that came w/ a special order color, and the only way you'll find it will be to find a complete list of all color numbers GM used around then - can you get a close idea from the firewall or door edges or behind the gas tank? was a pretty limited range if it was a standard color
Bill
