I have an '02 IS300 with 62k miles. Within the last couple of months, when you turned to the right, you heard this awful grinding noise on the left rear. It sounded just like metal on metal, which it was. The groove in the rear rotor was grinding against the backplate at the 6 o'clock position. I ground away the backplate and that made it better. I had to grind more material away (1/8" deep total) from the 4-8 o'clock position. It now has stopped.

Tell me what is going out and why! I have changed the rear differential fluid, but went back with the factory callout from the manual. No issues like gear clanging or chattering. The right side shows a little history of the condition (rusted scraping in groove) but nothing recent. Do these axles float? Is there a pin in the axle shaft that may have dropped and it allowing my axles to shift side to side?

You've got me confused.

Can you take pics and post them so I can see what your talking about? Have you checked all your bushings and sway bar?

I haven't checked the rear bushings and sway bar. I don't understand why these going out would cause the rotor to rub. The rotor is bolted to the rear backing plate via the lug nuts?

Ok, in the first picture, the disc is locked in place by the rotor and the lug nuts. There should be no rubbing issues. IF there are, then I think you were driving around with your lug nuts loose and it moved around. So long as the disc and rotor aren't structurally damaged it should be ok. You might want to check your lugs and stems to make sure they are properly holding also.

I can promise you the lugs were not loose. As far as the bushings and sway bar, they appear normal. No cracking, chunking, or shiny metal where the bushing has moved.