does anyone know how to tell which gear box is in my truck? 2003 gmc sierra 2500hd with the duramax 4x4 crew cab short box. there is a 32 spline or a 33 spline, i know i can take it out but i have to drive the truck to work and i want to be able to pull the old one out and install the new one at the same time and seeing as there is a 200 core on is. thanks for the help