I'm replacing the ps control valve on my 72 Corvette, I have everything disconnected but haven't been able to screw the unit off. I have sprayed it with a solvent and will try again tonight. Any suggestions on breaking the unit loose? Can I hurt any of the steering rods attached to it by twisting or banging? Any help would be greatly appreciated.

I just replace mine and had a little trouble getting it to turn also. Where the unit is is threaded on to the the steering mechanism it is split whith a small bolt that is tightened to hold it in place when you have it where you want it to stay. I removed that bolt and used a chisel to spread the threaded sleeve open a little so it would have a loose fit and I was able to turn it off. Some twisting and tapping with in reason shouldn't be a problem. I hope this helps, it sure is hard to find the right words to explain some things!

Some advice if I may. Once you're able to unscrew the unit be sure to count the turns. Put the new one on the same number of turns.

Thank you both for the suggestions.