Sierra Classic option package - what is it?

[Jim85IROC]

My 87 1-ton GMC is a Sierra Classic. I would have thought that the Sierra Classic was the name given to the 3/4 and 1 ton trucks that kept the old body style after the changeover in 88, but mine's an 87, and I've also seen an 85 or 86 Sierra Classic. What specifically is the Sierra Classic package, and how is it different from the standard Sierra?

For reference, the truck is a 1-ton 4x4 with a LOT of options. 454, TH400, power windows, locks, air, tilt, cruise, premium interior, 2-tone paint, etc. I haven't seen very many 1 tons loaded like this one.