Crown Royal

im about to buy a sub box that goes under my rear seat. i have a 2006 crew cab 150 and it says for the hieght of the box is 8" every where i look and i measured my seats and at the highest ponit its only 7 and 3/4 will it fit or not cuz i think it goes out of the sit abit like in the front?????? your advice would be helpful thank you