Do you still have the SPID with th trim and color codes?
A factory Russet truck would be a code 68. The only secondary colors I am showing in 77 are 12 White, 60 Santa Fe Tan, 65 Buckskin as being used with 68 as a regular production option.
http://paintref.com/cgi-bin/chipcrea...del=ChevyTruck
Some color shift here but the codes are correct.