I use the regular old power steering fluid from Pep Boys, amber in color and works fine. While the manual (on the older cars) may state it's OK to use ATF, the current formulation of Dexron/Mercon may not be compatable with the seals, etc in the steering system. I run the same fluid in both the '73 and the '86 with no problems or leaks.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.