The original spec is type A ATF. I rebuilt my steering gear about two years ago with a rebuild kit that included all seals, o-rings, and thrust bearings. It has worked well until the last month or so, it has become very stiff and hard to turn. Could the newer piston ring seals be incompatible with Dextron III which is what I filled it with.

Any suggestions what to look for in the way of damage? I could notice no visible wear during the rebuild and the preloads were ok (I have a 0-60 in-lb torque wrench to check it).

If it needs new circulating balls does anyone know of a source of these and other hard parts for it?

Wow, all these views and no replies? What do you all fill your reservoir with (my original cap says to use ATF)?

I used Power Steering Fluid from NAPA.

ATF and power steering fluid are not the same.
Especially Dexron.
Use p/s fluid.

But my cap says to use ATF. And so does the Pontiac Service Manual

I use power steering fluid

automatic transmission fluid, and power steering fluid are both a hydralic fluid. transmission fluids have different viscosities. thats why your cap has type A. powersteering fluid is a hydralic fluid also. my car had ATF in it. when i put everything back together ( engine out ect.) i will put ATF back in it.

Not sure if there even was "power steering fluid" back then.

Not sure if you can even buy "Type A" ATF anymore.

I use power steering fluid.

i have a Chiltons repair and tuneup book for Firebirds 1967 to 1981 recommends Dexron ATF for years 1967-1976 GM power steering fluid 1977 and later.

here's the '68 Owner's Manual recommendations. However, I have only used power steering fluid for as long as I can remember.
(Of course this was prior to Dexron having numbers behind the name as it changed. Don't know what the new improved Dexrons did to the stuff over time.)

Wow, been so long i forgot the early models used type A.
Dexron from GM is up to level #VI.
Its alot thinner for the newer style electronic shift trany's.
The internal passages are alot smaller.

Anyway, i've always used p/s fluid since i started drive'n in 75.

A couple years ago I spent hours looking for some type A fluid to use in my convert top pump. I never did find any.

Ironically, when cleaning out my parents home recently, I found some that my Dad had on the back of a shelf in their garage. He's been gone for 15 years and it is in the old style oil can so it has to be pretty old.

I use and prefer power steering fluid. The viscosity is correct for the system, and it does not contain the harsh chemical additives (viscosity modifiers) used in newer ATFs. Also, PS fluid is not dyed so if it leaks it won't stain so much.