Tech help needed soon

[Cornpatch MO]

my 64 Dodge is at the mechanic shop now. Trying to fix the power steering gear box with it still in the car. Needing to replace the large O ring at the steering shaft input side. There is a large "nut" that has several slots in it..about 3-4" in diameter. How do we get that nut loose? we have tried a hammer & chisel on the slots, and it won't budge. I expect there is a special spanner wrench. Any idea's on how to get it loose-short of using heat? Thanks for any input.............................MO

 

[miller]

If you were closer, I'd loan you mine. Pretty sure I got the idea from the manual, but I made my own. Actually slot sockets. Hammering on 'em will probably mess the tabs up.
Maybe a parts house, you could get the tools on loan?

 

[Cornpatch MO]

If you were closer, I'd loan you mine. Pretty sure I got the idea from the manual, but I made my own. Actually slot sockets. Hammering on 'em will probably mess the tabs up.
Maybe a parts house, you could get the tools on loan?

Problem solved................thanks for your help................MO