What power steering fluid should I be putting in my 69 Coronet ? I have ATF Type F for my 70 Mustang, would that be ok ? Also should the cap be vented ? It does say vented on it but I can't see any holes on it, I have fluid coming out of the top on full lock, thanks

Disadvantage of type F, if you have a leak it eats rubber, tie rod boots, ball joints, etc. Probably still has air in the system pushing fluid out can be a bitc_ to bleed sometimes.

Isn't there rubber within the system?

Well he** John every time I think I've got something figured out somebody uses reason. But every time I've had ps leaks for extended time my rubbers swell & turn soft. I know fix my leaks but

Back in the day I ran ATF but now I just run power steering fluid.

I believe the spec is for PS fluid, not any ATF. Some have run ATF, but the only time ATF ever got into my system (thanks wifey) I soon had a major leak at the pitman shaft seal. That one is a PITA to replace without the special factory tools in the car.

If you want to see the difference run one with each for a year and then look at the inside of the pump,one word, filthy.

Where do I get a replacement cap for the pump ?

The leak occurred because of the change in fluid, not what fluid was changed to. Common with aged seals.

Some of the rubber in later P/S systems is the exact same (even the same part number) that was in units back when ATF was the P/S fluid of choice.

2084329 was the p/s fluid mopar part number for older chrysler vehicles. the owners manual use to state not to use atf. i don`t know what would cause your issue though. are you over filling?