I have noticed there is a lot of confusion about G80 limited slip diff. in the 1985 third gen's. Post your build date,gear ratio,disc brake or not and if you have posi or open rear end. maybe we can figure out if there is a pattern. Mine is a Camaro IROC and it was built the second week of march 1985 "O3B' and I have GU6 G80 J65.

12/84 Van Nuys IROC GT4 G80 J65

January '85, 3.08, open, drums

On my 85 IROC there is a plate under the air duct above the radiator.. There is a sticker on the drivers side door that has the month and year of mfg, If it is still there.

I only know what some of the numbers mean, but if you can tell me what the build date is I'll add it to my original post.
The door sticker is too faded to read.

Edit: After seeing the edited original post, I think mine was built int the first week of january, correct?
Is it relevant to this thread where our cars were built? I know you can tell where from the VIN, (but I don't know what character should be what to identify it) but can you tell from this plate?

It looks like it was made the 1st week of Jan. 01A.

I have a 1985 Trans Am. I don't know the build date but it's a L69/5-Speed with G80, GS4 (3.70 Ratio), and J65.

As a side note: No such plate on my 85.

JamesC

I removed the air duct and looked above the radiator and found the tag on my 1985. It has 05C in the top left corner, the "05" would mean May and "C" would be the third week. On my door tag it only has 05 for the month and 85 for the year. I then looked at the original dealer invoice and saw that the car was shipped by rail on May 21st of 1985. In May 0f 1985 the third week of production started on the 13th a Monday through the 17th a Friday, then the car was shipped the next week on a Tuesday the 21st of May which sounds right. It has no G80 but has the 3.42 gears, also J65 and is original. I also saw on the top right side of the original radiator is a production date of April 24, 1985 which means it was made about 3 weeks before the car was built.

And I noticed there wasn't one on the '4.3 mile IROC-Z'...

Now you've got me curious whether some had the tag at some point in the production year or not! I see that with the information that others have given it had the tag if your car was built from January of 1985 till May of 1985. I'm wondering if the early 1985s that were built starting in August of 1984 through December of 1984 had the tags or not? Anyone have one built during those months with or without a tag under the air inlet duct?

The tag might be hit or miss.

http://www.thirdgen.org/techboard/hi...g-my-core.html

JamesC

I just went and looked at the "4.3 mile Iroc-Z" I noticed that it didn't have the LB9 fuel injected engine which has the air inlet ducts. Maybe the production tag is on a different spot if you had another engine in your Iroc-z? Anyone know for sure?

I have the same LG4 that the 4.3 mile car has, and I have it in the normal spot.
'LG4' is on my SPID sticker, and the VIN on that matches the VIN on my car, so I am sure my car has always had an LG4. And, the 6 digits on my tag riveted on under my hood matches the last six of my VIN.

My car was originally an LG4, no tag.

JamesC

I just read the thread that JamesC posted about the tags above and now its really confusing as to what years and models had them!

James, do you still have your door sticker, to tell the build date?

Edit: like posted in the thread James posted a link to, maybe they only installed these plates at a certain plant? Can someone remind me which number in the VIN I need to look at to tell where my car was built?

Edit #2: Thanks James. My #11 is an L. That means my car is from Van Nuys,

No, I don't.
Number 11. Norwood for me.

JamesC

Is my car from Van Nuys, since my #11 is an L?

Yes.

JamesC

I ordered my IROC 2/85 , build date of 4/85. Norwood, GU6, G80, J65. No plate under the air cleaner.

Do you still have your 85? When you ordered the GU6 G92 performance axle ratio did you have to order the G80 posi and J65?

My 12/84 Van Nuys IROC has the tag, it says 12C for the third week of December. I'm finding this really strange, I've been looking at all kinds of GM cars for almost 30 years, I don't think I've ever seen one without a trim tag!

Yes, I still have it. 24,000 miles. I don't rember if I had to or not. If I can figure out how to post an attachment, I will scan it and post it if this will help.

That would be cool.

Instructions for posting images can be found here:
http://www.thirdgen.org/techboard/pr...mages-tgo.html (How to post images on TGO)

If there is a problem, you can email me (jt@thirdgen.org) the images and I can post them.

Thank's for the link, I will post it later today when I get home from work.

I cannot find the original window sticker but I found this invoice instead. If I find the window sticker I will post it up. I will try to get some pictures of my SPID sticker tomorrow. Hope this helps.

Thanks for posting your invoice. I would like to see the spid and window sticker. Very nice IROC. Black with black int. Cool color combo. Is that the interior with camaro on the seats and door? Your int. code 19D was only ordered in 2,510 camaros for 85. thats only 3.7%. less with the 6 way power seats.That interior cost $875, that was a lot of money. It has K05 engine block heater only 6384 for 85. Very cool!

Yes it has the lear siegler interior, This was my first brand new car and i wanted a nice car. I only ordered the cheap radio because (as a young kid at the time) i was going to have a nice aftermarket system installed. As time went by i realized the car was more vauable stock. I am still looking for the window sticker ,and i will get some pictures of the spid sticker.

I think that in 1985 there were two ways to get the (GU6) 3.42 gear ratio. You could order a (B4Z) Iroc Package which changed the differential gear ratio from the (GU5) 3.23 that came stock in the Z-28 in 1985 to the stock Iroc gear ratio which was the (GU6) 3.42 in 1985. Then if you ordered the (G80) Limited Slip Differential with the Iroc Package in 1985 you would have automatically turned your car into a (G92) 3.42 Performance Differential equipped car without ordering the (G92) 3.42 Performance Differential because it was already there in the Iroc package. Just as "89RESTO" did when he ordered his new 1985 Iroc. If you didn't order the (G80) Limited Slip Differential with your (B4Z) Iroc Package it wouldn't be considered a (G92) Performance Differential equipped car in 1985. Or you could order the (G92) Performance Differential with either the stock Z-28 or the Iroc Package then you got the (GU6) 3.42 and (G80) Limited Slip Differential together in that (G92) Performance Differential Package without having to order these items separately in 1985. They came with these gear ratios if your car had the LB9 engine with the automatic.

My z28 had 3.08's stock, not 3.23's.

I should have said that if you had the LB9 fuel injected engine with auto like mine did, it came with the 3.23 gears in the Z-28 and 3.42 gears in the Iroc.

Here is my spid sicker and a picture of where the ID plate would be.

My '85 IROC has the LB9, 3.42, rear disc and NO posi. It was built in May.

I used to have an '85 T/A that had an open 9bolt, and drum brakes. I don't recall the ratio.

Thanks for posting your spid. It looks like the 1985 IROC's with the G92 performance axle got the same rear springs as the 1LE's, 8NN and 9NN. On your invoice is says central office. I wonder if the 205 G92 cars were COPO's.

When you post the pic of your window sticker. How about a few pic's of your IROC. I'd love to see it.

I haven't been able to find the window sticker but i will keep looking. I will see if i can get some pic's in the next few days.

mr396, are you saying that even though my spid sticker has no G92 option listed, It is still considered a G92 and that only 205 of these were produced in 85?

In 1985 the G92 included the GU6 3.42 performance axle, G80 limited slip and the J65 4 wheel disc brakes. Congratulations you have a rare IROC with only 205 made. as far as I know, You and I are the only one's here with this option. http://www.thirdgen.org/techboard/hi...re-asking.html and looking at your invoice and a L69 invoice, it looks like the 1985 LB9 G92 A4 and the 85 L69's were ordered through the central office. possibly COPO's. We need more info to confirm this. But It sure would be cool if they were COPO'S. http://www.thirdgen.org/techboard/hi...e-options.html

I just got back from taking some new pictures. I will get them on here later this evening.

Here are the first three, The car is all original including Gatorback tires, still the original belts and hoses. The only mods I made were a trans cooler and trans. temp gage,Both are critical for a700r4 if you ask me. I replaced the factory lug nuts because the caps kept comming loose and i didn't want to loose them, someday I'll re-install the originals. I apologize in advance for the seat cover but you know how easy these seats tear up and I just want to protect my interior.

And the next....

Next...

WOW! That is a beautiful IROC. Very cool. Now thats a keeper. Are those the original tires?

How about some pic's of yours ?

I only have the one. Mine needs a ton of work. it looks like it just came off the race track, I don't think there is one straight panel on the car. I saved it from pick a part. I only paid $300 for it. the interior is in great shape though.

i parted an 85 t/a L69 700r4 3.08 posi disc years ago

driver side was wrecked


dont know vin or date but i might be able to find papers still possibly

i cut the car up sold the rear and engine

New to posting, but not the site... I think I may have a g92. (No SPID, no plate, no paper trail) What I do know: 85 Iroc, built in Norwood 04/85, 305TPI, posi, 4 wheel disc brakes, 3.42 gears. Car seems to be 95% original, but not POSITIVE about drivetrain.

My 12/84 Iroc has the gu6, j65, g80, and also has the 8nn and 9nn springs.