Thomas, You got a slightly different story than I did but it is close enough. The thing I have issues with is the two number values of ~5600"/cy and 600"/cy. I got the same story as you did on this but I don't buy any of it because the generator at JPL/horizons clearly shows the position of Mercury's perihelion advances about 70 degrees or so in 4,000 years. That is relative to Earth and so it assumes only the positions of the Earth and sun are at the same point on a 360 degree orbit. No fuzzy thinking involved. I am in the process of inquiring about this and will post any new stuff. As to the 43" it seems to me it may be a left over relic as are a lot of things presumed to be facts.