silverstang84

Hey guys' I have an 86 iroc, I would like to find out more about my car through the RPO codes. I've searched this fourm but I can't find a gear ratio code for my car. Does anyone have a list of all the codes and what they mean? Thanks

83Z28/L69

http://www.drivetrain.com/parts_cata...chevrolet.html

Night rider327

iTrader: (13)

Here's a list to all of GM's RPO codes
http://www.marshu.com/images-website...-car-codes.pdf

Here's the third gen rear gear codes by year

GM 7.5"-7.625" 10-Bolt Axle Codes
1982:
2JE 2.73 Std 2JG 3.08 Std 2JH 3.23 Std 2JJ 3.42 Std
2JR 3.42 Posi 2JW 2.73 Posi 2JX 2.93 Posi 2JY 3.08 Posi
2JZ 3.23 Posi 2KE 2.73 Std 2KF 2.93 Std 2KG 3.08 Std
2KH 3.23 Std 2PE 2.73 Std 2PW 2.73 Posi 2PX 2.93 Posi
2PY 3.08 Posi 2PZ 3.23 Posi
1983:
4JF 2.93 Std 4JG 3.08 Std 4JH 3.23 Std 4JJ 3.42 Std
4JK 3.73 Std 4JQ 3.73 Posi 4JR 3.42 Posi 4JX 2.93 Posi
4JY 3.08 Posi 4JZ 3.23 Posi 4KJ 3.42 Std 4KK 3.73 Posi
4PG 3.08 Std 4PQ 3.73 Posi 4PW 2.73 Posi 4PX 2.93 Posi
4PY 3.08 Posi 4PZ 3.23 Posi
1984:
4PW 2.73 Posi 6JG 3.08 Std 6JH 3.23 Std 6JJ 3.42 Std
6JK 3.73 Std 6JQ 3.73 Posi 6JR 3.42 Posi 6JY 3.08 Posi
6JZ 3.23 Posi 6KK 3.73 Std 6KY 3.08 Posi 6KZ 3.23 Posi
6PN 3.73 Posi 6PQ 3.73 Posi 6PR 3.42 Posi 6PY 3.08 Posi
6PZ 3.23 Posi
1985:
4PW 2.73 Posi 6JG 3.08 Std 6JH 3.23 Std 6JJ 3.42 Std
6JK 3.73 Std 6JQ 3.73 Posi 6JR 3.42 Posi 6JY 3.08 Posi
6JZ 3.23 Posi 6KK 3.73 Std 6KY 3.08 Posi 6KZ 3.23 Posi
6PN 3.73 Posi 6PQ 3.73 Posi 6PR 3.42 Posi 6PY 3.08 Posi
6PZ 3.23 Posi
1986:
2EA 2.77 Std 2EN 2.77 Posi 2ET 2.77 Posi 8JC 3.42 Std
8JD 3.73 Std 8KA 3.42 Std 8KB 3.73 Std 8XA 2.92 Std
8XB 3.08 Std 8XC 3.27 Std 8XF 3.70 Posi 8XN 2.92 Posi
8XO 3.08 Posi 8XP 3.27 Posi 8XQ 3.45 Posi 8XU 3.08 Posi
8XV 3.27 Posi 8XW 3.45 Posi 8XX 3.70 Posi 8XY 2.92 Posi
1987:
2HA 3.23 Std 2HL 3.42 Std 2HP 2.73 Std 2HR 3.42 Posi
2HQ 2.32 Posi 2HT 2.73 Posi 4HB 3.08 Posi 4HR 3.42 Posi
4HV 2.73 Posi 4HY 3.23 Posi
1988:
6HT 2.73 Posi 6HE 2.73 Posi 6HP 2.73 Std 6HB 3.08 Posi
6HF 3.08 Posi 6HK 3.08 Std 6HL 3.42 Std 6HQ 3.23 Posi
6HJ 3.23 Posi
1989:
6HT 2.73 Posi 6HE 2.73 Posi 6HP 2.73 Std 6HB 3.08 Posi
6HF 3.08 Posi 6HK 3.08 Std 6HL 3.42 Std 6HQ 3.23 Posi
6HJ 3.23 Posi

1990:
8HP 2.73 Std 8HT 2.73 Posi 8HE 2.73 Posi 8HK 3.08 Std
8HF 3.08 Posi 8HB 3.08 Posi 8HJ 3.23 Std 2PM 3.23 Posi
2PN 3.23 Posi 8HC 3.42 Std 2PN 3.42 Posi
1991:
8HP 2.73 Std 8HT 2.73 Posi 8HE 2.73 Posi 8HK 3.08 Std
8HF 3.08 Posi 8HB 3.08 Posi 8HJ 3.23 Std 2PM 3.23 Posi
2PN 3.23 Posi 8HC 3.42 Std 2PN 3.42 Posi
1992:
8HP 2.73 Std 8HT 2.73 Posi 8HE 2.73 Posi 8HK 3.08 Std
8HF 3.08 Posi 8HB 3.08 Posi 8HJ 3.23 Std 2PM 3.23 Posi
2PN 3.23 Posi 8HC 3.42 Std 2PN 3.42 Posi

Borg Warner 7.75" 9-Bolt Axle Codes
1985:
10032243 3.08 Std 10032244 3.08 Posi 10032245 3.27 Std
10032246 3.27 Posi 10032248 3.45 Posi 10032250 3.70 Posi
10032268 3.08 Posi 10032270 3.27 Posi 10032272 3.45 Posi
10032274 3.70 Posi 14085324 3.42 Posi 14085325 3.42 Std
14085326 3.75 Std 14085327 3.73 Std
1986:
10032270 3.27 Posi 10032272 3.45 Posi 10032274 3.70 Posi
10040660 2.77 Posi
1987:
4ET 2.77 Posi 4EU 3.27 Posi 4EW 3.45 Posi
1988: 4ET 2.77 Posi 4EU 3.27 Posi 4EW 3.45 Posi 1989: 4ET 2.77 Posi 4EU 3.27 Posi 4EW 3.45 Posi

silverstang84

Weird, my code isn't there..

TTOP350

iTrader: (8)

Should be "GU_" codes for the 10bolt, not sure I've ever seen most of those for F-cars.

Night rider327

iTrader: (13)

That list Of rear codes will be the code on the axle housing it's self, not the RPO code. The RPO codes is in the link I posted.

Again the list of gear codes is the axle ID code stamped on pass side axle tube of the rear end

silverstang84

That clears that up then. Thanks

TTOP350

iTrader: (8)

That's odd that the RPO code doesn't match the item installed.

I have never looked for the axle code on these cars much (just 9bolt stuff), just my 2nd gen stuff.
I do know the rearend decal on the 9bolts match the rpo codes, wonder Y the 10bolts don't.

okfoz

Tony,
To answer your question to why codes are not the same as the RPO is it would depend on more than one factor. An axle can not only have the ratio, but it can have Ltd Slip (Posi), disc brakes, and in some cases the 1LE recieved a unique axle. (Ref 1988). Whether all of these were actually used... I have no idea...

Here are some conversions for RPO to AXLE Codes:
1987
GH3 4ET 2.77 Posi Disc Borg & Warner 9 7.75"
GM3 4EW 3.45 Posi Disc Borg & Warner 9 7.75"
GU2 2HT 2.73 Posi Saginaw 10 7.625"
GU2 2HP 2.73 Std Saginaw 10 7.625"
GU2 4HV 2.73 Posi Saginaw 10 7.625"
GU4 4HB 3.08 Posi Saginaw 10 7.625"
GU5 4HY 3.23 Posi Saginaw 10 7.625"
GU5 2HQ 3.23 Posi Saginaw 10 7.625"
GU5 2HA 3.23 Std Saginaw 10 7.625"
GU6 2HL 3.42 Std Saginaw 10 7.625"
GU6 4HR 3.42 Posi Saginaw 10 7.625"
GU6 2HR 3.42 Posi Saginaw 10 7.625"
GW6 4EU 3.27 Posi Disc Borg & Warner 9 7.75

1988
RPO Codes Axel
Code Ratio Type Manufacturer cover Bolts Carrier Size
G80, GH3, J65 4ET 2.77 Posi Borg & Warner 9 7.75"
G80, GW6, J65 4EU 3.27 Posi Borg & Warner 9 7.75"
G80, GM3, J65 4EW 3.45 Posi Borg & Warner 9 7.75"
G80, GU4 6HB 3.08 Posi Saginaw 10 7.625"
G80, GU2 6HE 2.73 Posi Saginaw 10 7.625"
G80, GU4 6HF 3.08 Posi Saginaw 10 7.625"
GU4 6HK 3.08 Std Saginaw 10 7.625"
GU6 6HL 3.42 Std Saginaw 10 7.625"
GU2 6HP 2.73 Std Saginaw 10 7.625"
G80, GU5 6HQ 3.23 Posi Saginaw 10 7.625"
G80, GU2 6HT 2.73 Posi Saginaw 10 7.625"
GM3 7EW 3.45 Posi Borg & Warner 9 7.75"
1LE, G80, GW6, J65 8EU 3.27 Posi Borg & Warner 9 7.75"
1LE, G80, GM3, J65 8EW 3.45 Posi Borg & Warner 9 7.75"
1LE, G80, GW6, J65 9EQ 3.27 Posi Borg & Warner 9 7.75"

1989
RPO
Code Axel Code Ratio Type Disc/ Drum Manufacturer cover Bolts Carrier Size
G80, BEU 3.27 Posi Saginaw 10 7.625
G80, GM3 BEW 3.45 Posi Saginaw 10 7.625
G80, GU4 6HB 3.08 Posi Saginaw 10 7.625
G80, GU2 6HE 2.73 Posi Saginaw 10 7.625
G80, 6HF 3.08 Posi Saginaw 10 7.625
GU4 6HK 3.08 Std Saginaw 10 7.625
GU6 6HL 3.42 Std Saginaw 10 7.625
GU2 6HP 2.73 Std Saginaw 10 7.625
G80, GU5 6HQ 3.23 Posi Saginaw 10 7.625
G80, GU2 6HT 2.73 Posi Saginaw 10 7.625
G80, 8ET 2.77 Posi Disc Borg & Warner 9 7.75
G80, GM3 8EW 3.45 Posi Disc Borg & Warner 9 7.75
G80, GM3 9ER 3.45 Posi Disc Borg & Warner 9 7.75
G80, GW6 9EQ 3.27 Posi Disc Borg & Warner 9 7.75
G80, 9ET 2.77 Posi Disc Borg & Warner 9 7.75

1990-1992 I think are all the same
Axel
RPO Axle
Code Code Ratio Type
G80 GU6 2ON 3.42 Posi
G80 GU5 2PM 3.23 Posi.
G80 GU6 2PN 3.42 Posi.
G80 GU4 6HB 3.08 Posi
GU6 6HE 3.42 Std
GU2 6HE 2.73 Std
G80 GU6 6HF 3.42 Posi
GU5 6HJ 3.23 Std
GU4 6HK 3.08 Std
GU6 6HL 3.42 Std
GU2 6HP 2.73 Std
G80 GU2 6HT 2.73 Posi
G80 GU5 6PM 3.23 Posi
G80 GU6 6PN 3.42 Posi
G80 GW6 8EV 3.27 Posi
GM3 G80 8EW 3.45 Posi
GU4 8HB 3.08 Std
G80 GU2 8HE 2.73 Posi
G80 GU4 8HF 3.08 Posi
GU5 8HJ 3.23 Std
GU4 8HK 3.08 Std
GU6 8HL 3.42 Std
GU2 8HP 2.73 Std
G80 GU2 8HT 2.73 Posi
G80 9ET 2.77 Posi

yo soy el warg

I looked at another rear code chart that I found and it is also different yet. It is laid out pretty good but doesn't match the GM repair manual.

http://sethirdgen.org/reardata.htm

But then here are the ones for 1985 in the GM repair manual. My 1985 IROC has the factory original RPO GU6 on the spid and (9PE) on the axle housing with 3.42 gears J65 4 wheel disks and no G80 in the differential. I have seen this listed for 1985 (Rear Axle: Positraction (G80) manditory when equiped with 4 wheel disc brakes). Which didn't apply to my car since it has no G80 and got J65 4 wheel disk brakes. Here they are and they seem to be correct for 1985.

Rear Axle Codes
8JB 3.23:1 8KR 3.08:1 8XP 3.27:1 Locking
8JC 3.42:1 8PP 3.08:1 Locking 8XQ 3.45:1 Locking
8JD 3.42:1 8PQ 3.23:1 Locking 8XR 3.70:1 Locking
8JP 3.08:1 Locking 8PR 3.42:1 Locking 8XU 3.08:1 Locking
8JQ 3.23:1 Locking 8PS 3.73:1 Locking 8XV 3.27:1 Locking
8JS 3.73:1 Locking 8XB 3.08:1 8XW 3.45:1 Locking
8KA 3.42:1 8XC 3.27:1 8XX 3.70:1 Locking
8KB 3.73:1 8XO 3.08:1 Locking 9PE 3.42:1

sofakingdom

iTrader: (1)

And, that code would be,,,, ..... ???

okfoz

I looked up the information in the parts catalog and it only had the 3.27 & 3.45 for 1987, and then only the information for the B&W axles for 1988 & 89, then the saginaw for 90-92... it also listed some of the 1989 codes with the 1990

I think one of the things that we have to wrap our heads around is for some years (in the US) the 350 only came with the J65 (unless you got the 91-92 J42), the G80, and the 3.23 axle... So if we could figure out the coding system we might be able to weed out some of these that were never used... At least in the US.

John