Pat: Back then and well into the 80s, there was no special power steering fluid. It was commonly Automatic Transmission fluid used for power steering. Mostly a Dexron II spec. BMW used a special fluid filling for cold climates called "Pentosin". Very agressive and toxic stuff.
When the Dexron spec changed and the manufacturers realized they could make money selling p/s fluid, they started to do so. Most of them slapped their logo on a proprietary bottle of ATF and called it P/S fluid. At Vickers, we based all our testing and performance specifications on the use of ATF.