S.K.
I agree with the other posters--he should still be in a 5-point harness.
The Babycenter.com car safety board has been very helpful for me in the past. The ladies on the board are Certified Child Safety Technicians. They can help you find the best seat for your child--just tell them your child's age, weight, torso height (from bum to shoulders), and the type of car you drive (and if you have other car seats that need to fit with the new seat, like if you have a three-across situation). The ladies on the board will respond very quickly and help you find the best seat for your child, your car, and your budget.
Here's a link to the site: http://boards.babycenter.com/n/pfx/forum.aspx?webtag=bcus...