I think they do. i know we did a group buy a while ago from rallylights.com (we still get 10% off cause of it) for the FF1000. which are the next step up from the 500s IIRC. you might need a different bracket (which IIRC rallylights sells) but they should go in the stock location.
And the actual lights.... http://www.yellowandbluelighting.com/Cart/ItemNF/tabid/86/List/0/CategoryID/101/Level/a/Default.aspx
And where I got my lights on the cheaper side... http://ptcfactoryoutlet.com/products-hella-refurbished.html They looked brand new. He takes parts fromnew lap returns or something and builds kits from them but can not callthemnew because there were sold or something. Call and ask. I forget why he can sell them that cheap.
I have the FF1000's from the group buy. They're a PITA to aim and really fawking bright. Prepair to get high beamed allot! But I sure do love'm, 2x as bright as the headlights, even the highbeams.