It way too much work to use stock headlight ballast to drive the fog. Doesn't worth the trouble in my opinion. You'll have to find pigtail connector to convert the fog H8 connector to fit into the stock ballast for the source, and then find connector to convert the ballast D2S output to H8 bulb. If you use the D2S bulb instead of H8 bulb, it will not seat and seal correctly at the fog housing. Just get the Restrofit SOurce 3Five Ballast. I have installed a couple of these. The wire harness and ballast is so beefy and quality built. I have ran with the DDM ballast and bulbs for years without any issue.