Originally Posted by puma1552

If you just bought a new 1985-1990 Camaro, and you aren't sure if it's an IROC or not, here's how you can tell. This document will only focus on determining if your car is an IROC, or not. It will not go into greater detail to determine exactly which model you have (Berlinetta, Sport Coupe, RS, Z28, etc.) beyond that. This post is mainly just to determine if you have the king of the hill IROC-Z or not. If not, you will need to use the site's extensive tech data to determine exactly which model you have, plain Z28 or otherwise. The tech data is available on the homepage here, in the left sidebar. Now, on to determining if you have an IROC or something else.

The best way to tell what your car is is by looking at the RPO codes, listed in the center console. These are de facto truths, as long as the VIN on the SPID (Service Parts Identification) matches the VIN on your cowl. However, in the event your car's console has been replaced and your SPID is long gone, it is possible in some cases to determine if your car is an IROC or not by the VIN; the VIN tells you what engine the car came with originally, not what trim model the car came with. However, as certain engines were only offered on IROCs in certain years, you can deduce that you have an IROC based on the VIN in some instances. Data is broken down by year below. In each year, the letters for each engine option refer to the eight digit of your VIN--that is the engine code. If at all possible, use the RPO codes to determine if your car is an IROC, rather than the VIN. Only look to the VIN for guidance if your SPID is missing.

If your car's model year is:

1985:

1985 IROCs used two different RPO codes--"Z28", and "B4Z". Plain Z28s will have just "Z28" in the RPO codes. IROCs will have both "Z28" and "B4Z", because "B4Z" is the RPO code for the IROC package, which was added on to the "Z28" package. For 1985, No "B4Z"=no IROC.

However, if your SPID is missing, the eighth digit of the VIN may be able to tell you what you have:

IROC Engines:

F (LB9)
G (L69)
H (LG4)

--In 1985, if your VIN shows a "G" in the 8th position, you have an IROC, because the IROC was the only model this engine was available in.

--In 1985, if your VIN shows either "F" or "H", the VIN tells you nothing about the car's status as an IROC, because these engines were also used in other models. You will need the RPO codes from the SPID.

--The RPO code to look for in 1985 is "B4Z". For this year, No "B4Z"=No IROC.

1986:

1986 IROCs used two different RPO codes--"Z28", and "B4Z". Plain Z28s will have just "Z28" in the RPO codes. IROCs will have both "Z28" and "B4Z", because "B4Z" is the RPO code for the IROC package, which was added on to the "Z28" package. For 1986, No "B4Z"=no IROC.

Engine options for 1986 were as follows:

IROC Engines:

F (LB9)
G (L69)
H (LG4)

--In 1986, the VIN tells you nothing about the car's status as an IROC, because all of the engine options were available on models other than just the IROC. You will need the RPO codes from the SPID.

--The RPO code to look for in 1986 is "B4Z". For this year, No "B4Z"=No IROC.

1987:

1987 IROCs used two different RPO codes--"Z28", and "B4Z". Plain Z28s will have just "Z28" in the RPO codes. IROCs will have both "Z28" and "B4Z", because "B4Z" is the RPO code for the IROC package, which was added on to the "Z28" package. For 1987, No "B4Z"=no IROC.

However, if your SPID is missing, the eighth digit of the VIN may be able to tell you what you have:

IROC Engines:

F (LB9)
H (LG4)
8 (L98)

--In 1987, if your VIN shows an "8" in the 8th position, you have an IROC, because the IROC was the only model this engine was available in.

--In 1987, if your VIN shows either "F" or "H", the VIN tells you nothing about the car's status as an IROC, because these engines were also used in other models. You will need the RPO codes from the SPID.

--The RPO code to look for in 1987 is "B4Z". For this year, No "B4Z"=No IROC.

1988:

In 1988, you could not purchase a Z28 that was not also an IROC. All Z28s were IROCs by default in 1988, so GM no longer used both "Z28" and "B4Z" RPO codes. Instead, they dropped "B4Z" and just used "Z28" on the SPID. In other words, for 1988, No "Z28" (RPO on the SPID)=No IROC.

However, if your SPID is missing, the eighth digit of the VIN may be able to tell you what you have:

IROC Engines:

E (LO3)
F (LB9)
8 (L98)

--In 1988, if your VIN shows an "E" in the eighth position, the VIN tells you nothing about the car's status as an IROC, because this engine was available in both the IROC and the Sport Coupe. You will need the RPO codes from the SPID.

--In 1988, if your VIN shows either an "F" or an "8" in the eighth position, you have an IROC, because the IROC was the only model these engines were available in.

--The RPO code to look for in 1988 is "Z28". For this year, No "Z28"=No IROC.

1989:

In 1989, you could not purchase a Z28 that was not also an IROC. All Z28s were IROCs by default in 1989, so GM no longer used both "Z28" and "B4Z" RPO codes. Instead, they dropped "B4Z" and just used "Z28" on the SPID. In other words, for 1989, No "Z28" (RPO on the SPID)=No IROC.

However, if your SPID is missing, the eighth digit of the VIN may be able to tell you what you have:

IROC Engines:

E (LO3)
F (LB9)
8 (L98)

--In 1989, if your VIN shows an "E" in the eighth position, the VIN tells you nothing about the car's status as an IROC, because this engine was available in both the IROC and the RS. You will need the RPO codes from the SPID.

--In 1989, if your VIN shows either an "F" or an "8" in the eighth position, you have an IROC, because the IROC was the only model these engines were available in.

--The RPO code to look for in 1989 is "Z28". For this year, No "Z28"=No IROC.

1990:

In 1990, you could not purchase a Z28 that was not also an IROC. All Z28s were IROCs by default in 1990, so GM no longer used both "Z28" and "B4Z" RPO codes. Instead, they dropped "B4Z" and just used "Z28" on the SPID. In other words, for 1990, No "Z28" (RPO on the SPID)=No IROC.

However, if your SPID is missing, the eighth digit of the VIN may be able to tell you what you have:

IROC Engines:

F (LB9)
8 (L98)

--In 1990, if your VIN shows either an "F" or an "8" in the eighth position, you have an IROC, because the IROC was the only model these engines were available in.

--The RPO code to look for in 1990 is "Z28". For this year, No "Z28"=No IROC.

Quick Summary:

1) 1985-1987 IROCs will have "B4Z" on the SPID. For these years, no "B4Z"=no IROC. If you just have "Z28" on the SPID, it's a plain Z28, and not an IROC.

2) 1988-1990 IROCs will have only "Z28" on the SPID. For these years, no "Z28" (RPO on the SPID)=no IROC. "B4Z" was not an RPO code used in these years.

3) An engine code of "8" for any car, 1987-1990, means the car is an IROC.

3) An engine code of "G" in 1985 means the car is an IROC.

4) For 1986, you must use the SPID to determine if you have an IROC. The VIN can't help you at all.

5) For 1987, an engine code of "F" or "H" tells you nothing. You need the SPID to determine if you have an IROC.

6) For 1988-1990, an engine code of "F" or "8" means you have an IROC. If you have an engine code of "E" (1988-1989 only), you need the SPID to determine if it's an IROC.

Originally Posted by F-body-fan

I searched for you & found this from another thread:

Originally Posted by 87zeder

sweet thanks a lot f-body fan.... your help is greatly appreciated!!!! I guess I do indeed have a IROC-Z awesome!!