After a quick search, here is an example that fits an existing housing
http://www.autotech.com/stracks.htm, here are some kits from Quafe
http://www.quaife.co.uk/catalogue/page60.htm, here are some for minis
http://www.minisportshop.com/Minispo...aries_485.html etc. I know there are some aftermarket, general purpose kits out there too..