Hi Bill, I am pleased to assist you. No, you do not need yellow bulbs if you replace the clear lens with a yellow lens. The yellow lens itself will filter the light from standard clear (white) bulbs and create the desired yellow light output. If you prefer a deeper or more saturated yellow light, you can combine the yellow lens with yellow bulbs, but this is not necessary for most applications. If your vehicle is compatible with the information provided on our website, you can use the link below to order while the part is in stock. Your order will come with a 30-day post-purchase price match guarantee. I hope this helps, and enjoy shopping! https://www.carparts.com/fog-light-lens/hella/h57pcg63121104?can=CPGG4850_CSQA_20241128