I think it was a place called RenTek who could supply them, but then saying that I had a customer contact me about the same bits as his order was taking about 6 months from them, so maybe they can't get them anymore?
I have done the bush in my rack. It was a cheap and easy to get (here anyway) Renault 16 steering rack bush. I believe the same one was fitted to Peugeot 504s as well.
GTA V6 Turbo
Renault 4CV 16TS Power
BMW 2002 Tii M3 Power