I had a headlight conversion kit that required 9004 bulbs, but I used 9007 bulbs instead. I couldn't find any difference bewtween them. The packages listed the same power usage, they had the same plug, and the same locating tabs. The only thing different at the time(3-4 years ago) was silverstars weren't available in a 9004 yet but the 9007 was so I got them instead. I cant see any reason why you cant use the bulbs you purchased.