Lexus: 2004 ES300 "clunking" noise when turning the steering wheel

My ES300 has been in the shop for 3 weeks due to a "clunking noise" when
reversing the direction of the steering wheel. The dealer service people say
a yoke in the steering column needs to be replaced but that Lexus does not
have any in stock. I asked if it was a common problem and he said it wasn't
common but had been a repeating situation enough to exhaust the supply of
replacement parts. We have a loaner Lexus so it really isn't bothering me
that it is taking so long but it seems kinda strange.

I was wondering if anyone else had experienced this situation or something
similiar with Lexus.