I use the Integy on mine and it holds up well. Eliminates the rear links. Usually Integy is junk, but this part is not a high stress one so it works OK.
http://www3.towerhobbies.com/cgi-bin...?&I=LXPZN0&P=7
If you want the higher quality HPI ones, go to Wheelspin in the UK. They don't sell them separately in the US. About 2 weeks shiiping to the US.
http://www.wheelspinmodels.co.uk/ite...uspension__4c7