You could look up Mr T part number on partsouq site. I buy a lot from them. Even with shipping from Dubai, some items are cheaper than Rock's and arrive quicker.
Interestingly enough, just as an example, genuine lug nuts from the local dealer had Made in USA on them, and partsouq shipped me Made in Japan cheaper. Did not have a pleasure fixing rear ones, but the front ones were either Timken or Koyo from Toyota. As others said, they have different lines and different QA. It is impossible to buy a real, genuine Lexus OE part, as they are created by their QA at the assembly factory from Toyota parts. We had a few interesting anecdotes with the same part failing in Landcruiser UJ100 and working fine in a Lexus LX470 line.