I've thought about this Mercury precession another way, that it is a 'momentum transfer' from the Sun's equatorial spin also, but that the numbers did not work out (though I had no way to work them out since I don't know this math) because Mercury was assumed to act as it's mass was computed from Newtonian orbital mechanics, then adjusted with GR. I thought (and this is my penny's worth) that if the mass was acting 'as if' it were, per equivalence to G, much less than measured (though remaining same mass), that this close body to the Sun would 'accept' more momentum transfer than Newtonian mechanics would allow. If, for example, Mercury's total mass acted 'as if' it were only about 40% (at about 0.39 AU) of what we know it to be, then the momentum transfer from the Sun would act as if it were 2 1/2 times what Newton's would calculate. But I never did the math, nor do I know at this point how to do it, so leave this here more as a doodle than a serious proposition. Otherwise, Grav, I am impressed with the work you did here!