This reedy rattle happens only when turning left, both at low speed (25 mph) making a left turn and at hiway speeds going around a curve. I looked underneath and there is a considerable amount of flimsy heat shielding on the left side where the exhaust train runs. There is also rust on the drive train universal joints. It sounds like it comes from the rear with the windows closed, and maybe from the front with the driver window open. 50k miles driven in Utah.
Rust on the U-joints is normal. (surface rust) Even (near) new ones on the lots have it.
Have a close look at those flimsy heat shields, they (it) is likely loose.