Well I've got a manual but I just got my 4.10s in today. Can't wait to get them put on! I don't do alot of highway driving though so I figured this would be a good choice. Used to have 91GT with 3.73s and those were great also. With an auto though, I wouldn't go with less than 4.10s, and I've heard good things from people with autos that went with 4.30s. Like a previous post, just depends on your preference.