T.S.
Hi E.,
At 2 he should definitely still be in a 5 point harness seat. We have the Cosco Alpha Omega Elite (also sold in an Eddie Bauer version), and my tall son (at age 2, over 3 feet) fits it just fine, with room to grow. Other options include a Graco 5 point harness booster and Britax offers one, too. It is dangerous to have him just in a shoulder harness at this age...his body is just too little to handle the impact of a crash. Good luck!