My UR RSB came with a black toyota OEM bushing (mbarton). I just finished regreasing them and my noise is 90% gone. OEM are too small for my 19mm rsb (oem is 16 mm).
http://img696.imageshack.us/img696/4154/sany0039x.jpg
The TSB on RSB is just a coincidence for people like us. It might be due to the geometry of the rear suspension. Anyways I noticed that the paint on my rear saw bar had eroded off under the bushing causing any uneven surface (the powder coating is very thicK). So I will have to sand and paint that if I buy a greasable poly.