Does anyone know how to use the VIN to find parts. I'm looking for the right power steering box for a 2002 Duramax 2500. It is either a 32 or a 33 spline with either 3 or 4 blanks. Last 8 of VIN are, "2F123243". I'm going to replace the pitman arm also so I don't know if it really matters as long as I buy the matching parts. ???