Option 1. use a vise (preferablly one with smooth jaws), invert 1st so nut is held by vise jaws, screw in a bolt (3/8", 7/16", 1/2" Fine Thread) into one of the ports, begin with a several lite palm taps, get heavier if needed.
Option 2. if you have an old monkey wrench, works nicely, or large cressant wrench.
Option 3. go out find/buy one each 1" and 26mm 3/8 drive sockets, return home, walk over to your metal lathe, cut the length down, bore a recess inside, one 3/8" extension, one ratchet. Took less than 1 hr. This is the better alternative, sockets will allow you to torque the nut back to factory spec.
If socket method not available, and you use option 1 or 2, when you re-assemble, make sure the threads (thrd) are clean, no oil or lube on thrds, use a drop of "BLUE" locktite, re-install nut, snug it up tight.
FYI: nut torque will generally run around 20 ft lbs, some as little as 8 ft lbs, either way I still like to use a drop of locktite. If memory serves me correctly, SP MK20, had an upgrade because overtightening the yoke nut lead to some damage problems.
Hope this helps..........carl
