Hey guys maybe you can help me out, i am trying to verify all my numbers on my 68z , the rear axle code reads bu 0214g1 casting b78 which all matches the car the part im not sure of is the code bu code, several books show the bu as a 3.37 and some show as 3.73 it has 3.73 in it now. i am just looking to see if anyone has had the problem? thanks for any input