Generally, automatics came with the NP203 "full time" and no lock out hubs, and manual transmissions came with NP205 "part time" and lock out hubs.
I think that started mid-year production 1973. My K20 that I ordered in Jan 73 with TH350 had the NP205 and hubs. It was quite a pain getting a new front driveshaft for it years later, as the parts catalog did not list a shaft for automatic and NP205. The one that finally fit was supposed to be for a 292 six and four speed
Sometime along the way - maybe 1980? - they went back to the NP205 for everything before switching to an aluminum TC (241 or something?). GM advertised this as a great new development that you could get a 4wd automatic with lock out hubs
My new 1980 was a four speed so it came with the NP205/hubs anyway. Unfortunately I had to sell it to pay for buying stuff to start a business.