Build sheet trans codes

[427-KING]

Does anyone know why the norwood buildsheet box codes for a m21 in a chevelle are XJ and a camaro its XG ?? Is this code similar to the WO code stamp on the trans tags that started in 1970? 

[JohnZ]

Does anyone know why the norwood buildsheet box codes for a m21 in a chevelle are XJ and a camaro its XG ?? Is this code similar to the WO code stamp on the trans tags that started in 1970? 

Yes, it is - that's the Broadcast code assigned to that transmission assembly part number. The only difference between two same-year M21's with different broadcast codes is the diameter of the pressed-on speedo drive gear on the output shaft; there was a "large" or "small" drive gear, depending on which range of axle ratios the transmission was intended to be used with.

[427-KING]

69 chevelle 355 w m21 XJ    69 camaro m21 373 XG and 69 camaro 373 m22 XH........ie are you saying the camaros and chevelles are the same code as long as the axle raio is constant? I assume then  if there were 410s in those 2 373 cars the code would  stay the same for the trans buildsheet box.   I may be wrong but the chevelle  m22 410 for 70 ls6 is WO while the camaro L78 w 410 is not..