Looking at the transfer case cross member I'm going to guess 85~87.
6" lift, 35" tires, Progessive wheels. Custom Deluxe, K10. Light blue metallic. NP208 transfer case.
Really, really hard to nail down a year on the 81~87 trucks looking at the side or rear. Front would be awesome. Can get within two years with a grille pic.
Tailgate net, saw blade wheels, roll bar, that truck looks like 90% of the square bodys around here circa early 1990s. A truck exactly like that was my dream truck back in the day. (See my build thread) Thank goodness your dad didn't put a sun visor on it.