It has been discussed before.
If you want to have it in the Turret, you would best be 4'2". There is a box under the Crew commanders chair that restricts his up and down range of movement. There is a box under the Crew Commanders foot rest that takes away six to eight inches of leg room and causes the Commander to have his knees in his chin when he drops down to use the sights. There is a monitor mounted between the Commander and Gunner which restricts them both to visually check each others drills and is in the way of the Main Ammo bin. Therefore you should be 4'2" to feel comfortable in the turret, abut that monitor gets in the way, no matter what size you are.