The pinion nut is tightend to torque only if pinion preload is shim adjusted. Which, from what you have said, is not the case with a 9".
With the crush sleeve design, it is not tightened to a specific torque, it is supposed to be tightened to achieve a specified pre-load on the pinion bearings.
The torque required depends on how stubburn the crush sleeve is. It takes several hundred (2-300) foot-pounds to turn the nut, then you test for a few INCH-pounds of bearing preload (probably around 15 with used bearings, but I don't know the spec)
If you were just doing a seal, you could mark the shaft and nut with a center punch, and just "clock" the nut to the same position you found it in.
Since you are changing the yoke, this won't work, (because new yoke won't be exactly the same length as old oned) and you'll need to set the preload, and that will probably require a new crush sleeve. You'll either need an inch-pound torque wrench, or rig up a lever and weight arraingment. (1 lb weight on 12" lever = 12 inch pounds) It is tricky with diff installed, as there is only a few degrees of backlash where you can feel the preload.
The locking feature of the nut makes it hard to tell if you have contacted a used crush sleeve yet when you get to the correct preload. With a new crush sleeve, you have to get over the hump of getting it started crushing, and bearing is still sloppy at that point, so there is no doubt.
There is not a lot of difference in feel between too-loose, and way too tight. Too loose will damage gear teeth, and too tight will burn up pinion bearings, so there really is no workable shortcut to doing it right. Crush sleeve is lots easier than changing preload shims, so don't bitch.
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