Yep, H4 with Hi/low. Here is the kit I have been running in 2 atvs and 2 trucks for several years now. Had a DOA bulb once but they replaced it for free. They are very bright, very cheap, and take a beating. If break one(haven't yet) I will buy a new set and have spares.
EDIT: I use the 55w at 6000k. I may switch to 5000k at my next set. 6 is a little to blue for my liking.
You won't need the adapter cable or error eliminator. IIRC, you don't need the wiring harness either, as long as you get the Hi/Lo kit. If you get the standard kit, AND 55w, you need the harness. Otherwise, just pick the wattage, bulb type, and color temp.do I need the harness or adapter cable?
or anything else ?
Well if you get the Hi/Lo kit, which I would recommend doing, you don't need either harness. But if you get the low beam only kit, then you need a harness. Either harness will work, but the dual relay uses a separate relay for each headlight, so if one relay fails, you still get out of the woods with at least one headlight. With the single relay harness, if that relay fils, you have no lights at all. For $5, get the dual.Do you need the single or dual relay? For the HId lights? Fordman