What transmission/transfer case do I have?

[hatzie]

The only stock case in the 1980 is the NP205 that uses 85W90 GL-5 gear oil. Some K30 with Auto Hubs got synchronized gearshifts. Use GL-4 in the Synchronized cases.

The 1979 & prior NP203 uses SAE30W non detergent

The 1981-1988 NP208 uses AC Delco 10-4033 or GM 88861800 Manual Transmission Fluid. Mobil1 ATF with GM 88861800 listed on the label or Pennzoil Synchromesh fluid will work. Usually the Delco fluid is cheaper unless you're buying from the dealer.