MAYBE a custom swingarm and/or linkage.(probably).
the rules state the swingarm must be stock.
and if i am not mistaken, the engine cases and frame must be as well.
ok, here is the rules for 2008:
a. Swingarm must be the same as an originally homologated model of the same manufacturer.
b. Strengthening gussets or tubes may be added, but none may be removed.
c. Chain guides may be removed or relocated.
and as you will find, same wording for the frame and cylinder.
http://www.amaprorac... 2008 Rules.pdf