if it is only 660 thousandths of an inch your looking roughly half inch in the shaft. are you using slip yoke and lift or no. if you have a lift at all you will be fine no questions asked. if stock then i would just push it all the way in and see how much room you have until it bottoms out. you need to figure in how much room you need for jounce of the suspension. im thinking your gonna be fine with waht you have. see what other replies you get say. see ya
jamie
jamie