hope this helps.
IN YOUR GLOVE BOX THERE ARE CODES GM USE'S.
TO FIND OUT WHAT GEAR RATIO YOU HAVE HERE THEY ARE: GU4 IS 3.08 .... GU6 IS 3.42 .... GT4 IS 3.73 AND GT5 IS 4.10 THESE ARE THE GEARS THAT COME IN 81-04 FACTORY AND IF THERE IS A G80 BY THOSE CODES ITS POSI.