[amc49]

Power steering fluid IS ATF with no dye in it and minus some ATX additives to make it cheaper. The only specific PSF I know of is Honda type for the plastic impellers those have in them.

The later Dexron 6 only shows up because it is more plentiful now, the fluids are the same but 6 is at least partly synthetic where the earlier wasn't. Same as what Ford did changing from Mercon to Mercon V then Mercon lo-vis, all work as power steering in anything other than a Honda that needs the special stuff. The dealers simply use whatever is the common one in the shop at the time.