Brakes in 1973-1991 Suburbans

[AutoandHVACnut]

Even though I am a diehard Chevy truck fan, at the moment I am driving a 2010 Toyota Tacoma (plan on adding a full-size Chevy 4x4 to my driveway when I get the money). Anyway, I was at the Toyota dealer dropping my truck off for routine maintenance, and I met this guy who was there with his wife dropping off their Toyota. He was in a 1983 Chevy Suburban K2500. Imagine my surprise when the guy tells me his Suburban has 4-wheel drum brakes. I know for a fact I have seen 1970s and early 1980s Chevrolet/GMC full-size trucks and SUVs with a front disc/rear drum setup. This 1983 Suburban had power-assisted brakes as well as power steering, but it had drum brakes all around. I looked underneath the truck and confirmed this. This was a fairly basic Suburban with no power windows and locks, but it did have automatic transmission, air-conditioning (which the guy said had been converted from R-12 to R134a and was in perfect working order), the factory AM/FM stereo cassette, and cruise control, so it wasn't one of those no-frills, A/C-delete, AM radio base model Suburbans that you see occasionally. Were front disc brakes like an option or something? I know I have seen 1967-1972 Chevy trucks with factory front disc brakes so it makes no sense why an early 1980s Suburban has 4-wheel drum brakes.