Automatic Transmission Fluid as Power Steering Fluid

I'm wanting to flush my power steering system.
In my early model Mustang my mechanic shop teacher told me its ok to use automatic trans fluid. Thats exactly what I did.
As the years have passed and the old Mustang has found a new home. I now own other vehicles and have always just bought bottles marked as "Power Steering Fluid" (clear fluid).

Me knowing what I know. I am aware that trans fluid has excellent cleaning properties. I was thinking I could flush the system with ATF and be a happy camper.

Any thoughts or advice on this would be cool.

Thanks

I used ATF in every Ford pump Ive had and havent had a problem.

Thanks for the reply.
The old Mustang pump was from the 60s or 70s so I wasn't sure how it would effect the newer ones.

Did you use type F fluid or would Mercon be o.k ?