Rear axle question

[rjg1987gn]

I have just purchased a low mileage, non-raced/dragged '87 GN. Everything checked out except for the rear end. The code on the pass side front facing axle tube is "2TJ G 329". The RPO code sticker on the trunk listed code G80 limited slip diff.

I looked up axle codes. Code "2TJ" is for a '86 GN however I cannot confirm what the "J" stands for.

I am pretty sure my '87 was bulit early on in the production run .

My questions:

Is "2TJ" an '86 GN axle?
.
Since an early production run would the factory use leftover '86 axle tube on a early '87?

What does the letter "J" stand for in the axle code?

PS I plan on pulling the cover off the rear end to confirm gear ratio and whether limited slip.

Thanks
Rick

 

[davelostmissing]

No metal tag on the cover?

 

[rjg1987gn]

No metal tag on the cover?

No metal tag on the cover.

 

[mikestertwo]

PS I plan on pulling the cover off the rear end to confirm gear ratio and whether limited slip.

Thanks
Rick

You don't have to pull the cover to verify either gear ratio or limited slip. Just jack the back wheels off the ground, put the trans in neutral, rotate one of the rear wheels by hand....the opposite wheel should turn in the same direction...that will verify if it is a posi. To check ratio....turn the rear wheel exactly one turn while observing the pinion yoke (assuming it is a posi). The yoke should turn slightly less than 3 1/2 turns.

 

[bison]

I don't think I've ever seen a metal tag on an 84-87 turbo regal diff.

 

[salvageV6]

Neither have I, but I keep looking.....

According to the service manual for 1987: 3TJ is the code for standard axle 8.5" gear 3.42 GU6 RPO.

3TP is the code for limited slip with the same specs.

But I'd have to go check a car to be sure as both mine are limited slippers.

 

[salvageV6]

Okay just checked the GN, got dirty, and found a return hose gas leak on salvageV6 the WE4.

Thanks a lot.

The GN I bought used but with G80 limited slip has the 3TP code with G80 stamped an inch or so to the right of the first code.

I'd double check yours with the 2TJ code it may not be limited slip.

 

[turbofish38]

Axle codes are the same for 86 and 87. 2TJ is non-posi. The letter J is part of the code. Not part of the build date. If you do indeed have G80 on your SPID label than I'm guessing either a previous owner swapped out the axle or the wrong part was installed on the assembly line. In all my years I have never ran across,as far as Turbo Buicks go ,where the wrong part, especially a major sub assembly like a rear axle, was installed on the assembly line. If you know how they were built than you would agree with me on this statement. Another possibilty would be that somebody made a reproduction SPID label and added the G80 to the new label. People have to remember these cars are 25 years old and anything and everything was done to them. One way to prove me wrong would be to purchase a copy of the vehicle invoice showing that G80 was ordered. GM never stamped the VIN on axles so there might be no way to prove it's not the original axle. The number 329 is the build date. It just means 329th day of the year. Since 2TJ is used for both 86 and 87 than we know it was built on November 24th. A legitimate date for an 87 GN. You should be able to narrow it down further by checking the build date on your cowl tag. Plenty of information on decyphering cowl tags and build dates on this site.

 

[rjg1987gn]

Axle codes are the same for 86 and 87. 2TJ is non-posi. The letter J is part of the code. Not part of the build date. If you do indeed have G80 on your SPID label than I'm guessing either a previous owner swapped out the axle or the wrong part was installed on the assembly line. In all my years I have never ran across,as far as Turbo Buicks go ,where the wrong part, especially a major sub assembly like a rear axle, was installed on the assembly line. If you know how they were built than you would agree with me on this statement. Another possibilty would be that somebody made a reproduction SPID label and added the G80 to the new label. People have to remember these cars are 25 years old and anything and everything was done to them. One way to prove me wrong would be to purchase a copy of the vehicle invoice showing that G80 was ordered. GM never stamped the VIN on axles so there might be no way to prove it's not the original axle. The number 329 is the build date. It just means 329th day of the year. Since 2TJ is used for both 86 and 87 than we know it was built on November 24th. A legitimate date for an 87 GN. You should be able to narrow it down further by checking the build date on your cowl tag. Plenty of information on decyphering cowl tags and build dates on this site.

Thanks for the information.

I see a different answer for axle codes from another source --Turbo Regal Web Site- Axle Codes from Steve Dove's Book and the Service Manual indicats 2TJ is for a '86 and 3TJ is for a '87. What is your source?

The cowl tag build date is the third week of August '87--so it looks like rear axle tube at least is not origional to the car. All other codes on cowl tag seem to check out. Reading left to right top to bottom: H08C, 4GJ47, p, oo6283, 19L, 190, words LACQUER, 82C, AR9, *11, 79.

Rick

 

[bison]

The cowl tag build date is the third week of August '87--so it looks like rear axle tube at least is not origional to the car. All other codes on cowl tag seem to check out. Reading left to right top to bottom: H08C, 4GJ47, p, oo6283, 19L, 190, words LACQUER, 82C, AR9, *11, 79.

Rick

That would be late 87. Im pretty sure all those had limited slips. They did some weird things at the end