C = 2 wheel drive, K = 4 wheel drive, V = 2 wheel drive, R = 4 wheel drive. 10 = 1/2 ton, 20 = 3/4 ton, 30 = 1 ton, All 3/4 and 1 tons came with 8 lugs. Not all one tons had bud / dual wheels.
Custom deluxe is base model, now power, Scottsdale useually had AC and some trim options, Silverado was loaded.
Welcome to the site from New Hampshire.
Just going by your name, do you have a 70 Cutlass? I have always liked the looks of that vintage. My brother had a 69 rag top when I was a kid, red with white top, and interior. That was the coolest car.