They are optional on the convertible. Same goes with the Stage 1 and 2 cars. They are standard on all 3 Stage 3 cars.
If I read the page right, convertibles come with sub-frame connectors from the factory. Roush uses different sub-frame connectors to clear the side exhaust.
http://www.roushperf.com/mustangconv.htm
[This message has been edited by Ares (edited 09-27-2001).]