Just the front one I believe. I did both, which did require moving the alternator bracket, breaking a coolant elbow without me knowing, causing a leak. $4 later new elbows were on, oh and $10 for coolant. If I knew I was going to flush it a month later, I would have just added 3/4 gallon of water. Anytime I will do valve cover gaskets in the future on a 3.8, new elbows will be bought. Unless they're aluminum(already replaced).