I mistakenly put power steering fluid in my transmission.
 

I'm a dope. I had my wife pick up a quart of Valvoline Maxlife
ATF while she was out shopping at Walmart. I even gave the empty quart bottle so she'd know "exactly" what to buy. She bought Valvoline Maxlife power steering fluid instead of ATF. In her defense, the bottles are indentical, except of course, one says power steering fluid and the other says ATF. Anyway, after a cursory glance I just took it out of the bag and topped off my transmission with the whole quart. I didn't realize this mistake until after I drove the car for about 25 miles, then looked at the bottle when I threw it away. My question is what, if any damage could this cause to my car. It's a 67 Catalina 2+2.

Also, I'll probably flush the transmission. Which line is the transmission return on the radiator. I believe it's the top one but I want to be sure.

Thanks.

No damage...

You sholld be fine. I wouldn't even worry flushing the trans. Both are hydraulic fluids, designed to do essentially the same thing. The power steering fluid shouldn't have any additives to hurt anything.
Change the fluid and filter again(drive it 1000 miles first) if it will make you feel better.

It used to be common practice to put ATF in the power steering resovior when topping off-Whats the difference. No big deal.

Great. 3 "no problems" sound good to me.

Thanks

how about a 4th and lets call it a day!:)