I just got a 1959 Coronet that has a transplanted 1974 400/727.

Which power steering fluid should I use? It's too low to touch dipstick so I can't tell if it's ATF or regular P/S fluid. It's the round neck... the 1.06 I think....? I really need to get some more fluid in it.

Thanx!

That`s a good question. You could dip a clean paper towel in enough to get some fluid on it. This is what I use in my 77. https://www.amazon.com/CRC-SL2641-Power-Steering-Fluid/dp/B000M8Q1ZS Since I couldn`t find the old mopar fluid anywhere.

From my 73 FSM, sorry no 74

On the 1.06 pump (Fig. 34) when the fluid is
checked when hot, the fluid level will be approximately
1/2 to 1 inch below the top of the filler neck.
At room temperature (approximately 70 degrees F.)
the fluid level should be above the joint of the filler
neck and reservoir (between 1-1/2 to 2 inches below
the top of the fiiller neck).
Units equipped with a dipstick (Fig. 35) should be
filled to the required indicated oil level.
If necessary to add fluid to restore these levels, use
only petroleum fluids specially formulated for minimum
effect on the rubber hoses, Power Steering
Fluid. Part Number 2084329, or its eqpivalent, is recommended.
Caution: Do not use Automatic Transmission
Fluid.

So... it's not ATF.

I will go from there.

Thanx for the response/info!!

The original '59 P/S fluid was Type A ATF which is still available but the ingredient that made it unique is no longer available.

Universal P/S fluid is a suitable replacement and is compatible with both the '59 box and the later P/S pump.

I went with regular fluid.... so far so good!

Now the pump is nice and quiet.