I think you can. I got 3.55 gears in mine, but I remember 3.73 being an option too. I went with 3.55 because I do a lot of highway driving and I didn't want to be at 3000 rpm the whole time. With the 3.55s, I'm at 2000 rpm at 65mph. I have an auto trans. I got the gears and traction lock put in at the same time by the local Ford dealer for about $500. You could probably have an independent shop do it for less. And, the gears do make a difference, especially on the highway; when I go to pass someone it's effortless.