Stickbow50

are the rear suspension knuckle for a1999 Lexus es300 and a 1999 Camry interchangeable

Oro

Neither of those cars, or most all cars, have a rear "knuckle" - maybe you mean a control arm, sway bar end link, or something?

The easiest way to tell is look up the part you want at a site like RockAuto, then compare the pn to the Camry one. Easy to see if they are the same. Many parts are indeed interchangeable like that.

LeX2K

Carrier, knuckle or whatever you want to call it there is one.

Linky

Same part for the ES and Camry with ABS. It's about the last part of the car to go bad I'd say.