Rear gear ratio RPO code list
 

Re: Rear gear ratio RPO code list
 

To answer your question, No there were no changes from year to year for RPO codes. GU2 is always 2.73 for example.

As per FIREBIRD PARTS CATALOG, Camaro would be same or similar
1982: - 10 bolt 7.50" Saginaw
GU1 - 2.41
GU2 - 2.73
GU3 - 2.93
GU4 - 3.08
GU5 - 3.23
GU6 - 3.42

1983: - 10 bolt 7.50" Saginaw
GU2 - 2.73
GU3 - 2.93
GU4 - 3.08
GU5 - 3.23
GU6 - 3.42
GT4 - 3.73

1984: - all 10 bolt 7.50" Saginaw
GU4 - 3.08
GU5 - 3.23
GU6 - 3.42
GT4 - 3.73

1985:
GU4 - 3.08 - 10 bolt 7.625" Saginaw
GU5 - 3.23 - 10 bolt 7.625" Saginaw
GU6 - 3.42 - 10 bolt 7.625" Saginaw
GT4 - 3.73 - 10 bolt 7.625" Saginaw
GW6 - 3.27 - 9 Bolt 7.75" Borg & Warner
GM3 - 3.45 - 9 Bolt 7.75" Borg & Warner
GS4 - 3.70 - 9 Bolt 7.75" Borg & Warner

1986:
GU2 - 2.73 - 10 bolt 7.625" Saginaw
GU4 - 3.08 - 10 bolt 7.625" Saginaw
GU5 - 3.23 - 10 bolt 7.625" Saginaw
GU6 - 3.42 - 10 bolt 7.625" Saginaw
GT4 - 3.73 - 10 bolt 7.625" Saginaw
GH3 - 2.77 - 9 Bolt 7.75" Borg & Warner
GW6 - 3.27 - 9 Bolt 7.75" Borg & Warner
GM3 - 3.45 - 9 Bolt 7.75" Borg & Warner
GS4 - 3.70 - 9 Bolt 7.75" Borg & Warner

1987 & 1988:
GU2 - 2.73 - 10 bolt 7.625" Saginaw
GU4 - 3.08 - 10 bolt 7.625" Saginaw
GU5 - 3.23 - 10 bolt 7.625" Saginaw
GU6 - 3.42 - 10 bolt 7.625" Saginaw
GH3 - 2.77 - 9 Bolt 7.75" Borg & Warner (No Firebirds reported with this axle in 1988 no data for 1987)
GW6 - 3.27 - 9 Bolt 7.75" Borg & Warner
GM3 - 3.45 - 9 Bolt 7.75" Borg & Warner

1989:
GU2 - 2.73 - 10 bolt 7.625" Saginaw
GU4 - 3.08 - 10 bolt 7.625" Saginaw
GU6 - 3.42 - 10 bolt 7.625" Saginaw
GH3 - 2.77 - 9 Bolt 7.75" Borg & Warner (No Firebirds reported with this ratio)
GW6 - 3.27 - 9 Bolt 7.75" Borg & Warner
GM3 - 3.45 - 9 Bolt 7.75" Borg & Warner

1990 ~ 1992 - 10 bolt 7.625" Saginaw
GU2 - 2.73
GU4 - 3.08
GU5 - 3.23
GU6 - 3.42

Re: Rear gear ratio RPO code list