Factory NP205 speedometer setup

[Toro]

Does anyone know if every 4WD with NP205 came from the factory with a speedometer gear adapter? I am the 2nd owner of a '72 Blazer that the PO left pretty much stock beyond adding a cup holder console. 350/TH350 with NP205 and 3.07 rear. Date tag still on transfer case, and tag still on rear diff cover. When I bought it, it had a 1.3 gear adapter which increases displayed speed. The speedometer has always been way fast. I removed the adapter and screwed the speedometer cable directly to the transfer case. A quick comparison to GPS has it showing really close, but I plan on driving a known distance of miles, and then checking how many miles speedometer shows as traveled to be sure. So now, I'm trying to figure out if these adapters were there always, or only with a config change when adjustment was necessary.