OK so now the question is, since I have replaced the steering rack with one from Advance Auto about 2 years ago do I still go by the owners manual recommendation?
Assuming that it was a Direct Replacement Aftermarket Part, and the Part did NOT come with special instructions stating it needed different fluid then required by the manufacturer, then YES, you still use what is recommended for fluid in the owners manual.
Most of the direct replacement aftermarket parts are from the Manufacturer's suppliers, rebuilds of the actual Manufacturers Parts or the same design manufactured under license by another company. So, its safe to assume, unless it came with special instructions, it has the same requirements as the original part it is replacing.
My manual states Chrysler power steering fluid not ATF+4.
My owner's manuals say to use PS Fluid that meets or exceeds Chrysler Spec MS5931 or MS9933 or MS9602.
All the manufacturers change the fluid requirements for their vehicles every couple of years because of the changes in technology. And newer technology is usually more demanding on the fluid, so Chrysler Fluid that met the demand in 1970, would very likely NOT be suitable for a new vehicle that stipulates a Chrysler Spec from 2008. If the aftermarket company just states its good for Chrysler Vehicles? Well which Chrysler Vehicles? The ones from the 1970's? My Jeep Commander uses a new Chrysler Spec above the MS9602. If Chrysler doesn't use the same PS fluid in all its vehicles currently, how can an aftermarket fluid claim its fluid works in all Chrysler Vehicles?
Finally, check the TSB's, like Imperial Crown just posted, Chrysler will test and assess their newer fluids for retrofit and if they find it suitable they will publish that information in a TSB. So, a TSB later then your Owner's Manual states something different, you can go with that TSB's advice.
And for the 2001 RS platform, that TSB is confusing and you'll need a build sheet to determine if you can retrofit or NOT.
If you have a replacement steering rack, unless you can find more information, you are going to have to assume, at the very least, the rest of the PS system that you did NOT replace (pump, reservour and hoses) could be the reason they did NOT recommend retrofitting to the new fluid. So I'd stick with what the TSB and Owner Manual says, despite having replaced the steering rack several years later.
The other question is does anybody know of an equivalent to the Chrysler power steering fluid that is from a different manufacturer?
Again, which spec Chrysler PS Fluid? I'm assuming from your previous statements, its NOT MS9602 (which is ATF+4). So, its likely MS5931 is the spec PS fluid your vehicle requires. If its NOT on the bottle, then look up the literature, it should say something to the effect, "Meets or Exceeds Chrysler spec MS5931". Then I would use it.