I am new to the 3rd gen scene, and new to this site, but have been a gear head for over 30 years. I just bought an '84 TA, L69 5.0 H.O. with 700R4 and posi. I've owned it less than a week. My question is... how do I tell if I have the standard 3.42 gears or the optional 3.73? It doesn't appear to be part of the VIN. Is it on the axle housing or anywhere else on the car? I don't have a build sheet or any other documentation. Thanks in advance for sharing your knowledge.

 

Take off the cover and look.

The fluid needs changed anyway; prolly been there since 1984. The ratio is stamped on the edge of the ring. It'll say something like "41:11" which is 3.73 (41/11 = 3.727272727272....). In 84, prolly half or more of the auto cars got 3.42, so odds are better that that's what yours has, but you never know till you look. No matter what it came with, it could have been changed.

If it has posi - most don't - it's most likely an Auburn POS or an even worse Eaton Gov-Lok. Probably 90% were the Auburn, the rest were the Grenade-Lok. If you have an Auburn (rare) and it still works, that's even rarer, and you're lucky. If you have a Gpv-Lok, which fortunately isn't too common unless somebody got one out of a S truck and put it in there, then you're not so lucky at all. If you can't identify it, take a picture showing what's inside the window of the carrier, and we'll be able to tell you what it is at a glance.

 

There is a code on the axle housing. I don't remember which side it is on. I used a wire brush and some carb cleaner on mine. The Chilton repair book you can buy at autozone or oreilly will tell you which side it's on and also list all the codes from the rearends with the gear ratio they have. There is also a way to do it by jacking the car up and marking the location of the wheel, then spin the wheel one complete turn and see how many times the pinion turns in relation to the wheel.

 

Check the RPO sticker on the bottom of the console lid. GU6 is the 3.42, GT4 is the 3.73 and G80 is limited slip (posi).

 

If u Jack it up and spin the wheel and both don't turn u have to make two revolutions and also sign of weak posi

 

Thanks to all for your input, especially Big Gear Head. I located the label under the console. It shows a G80 and a GT4. So I guess I have a 3.73 posi. It also shows WS-4 in one column and WS-6 in the column right next to it. Could this be a WS-6 car? Does anyone have a diagram of how to decipher the SPID label.

 

If it has RPO WS6, then yes it's "a WS6 car" (no dash). Not that it particularly matters; all WS6 is, is basically the most handling-oriented suspension in any given year. No magic in it. The exact details of what it included changed from year to year. It didn't become the buzzword that it is today until they stuck it on the side of some 4th gen TAs: that is, I don't recall ANYBODY asking on here "is my car a WS6" until about 98. It consists mostly of sway bars, polyurethane sway bar end links in some years, and springs, and in other years maybe a couple of other things. In 84 it didn't include posi or disc brakes or 16" wheels for example. But: any stock 84 springs are completely worn out and sagging and used up and in need of replacement, and there's LOTS of springs that are MUCH better than ANY of the stock "WS6" ones, especially the ones in the early years of these cars which were much softer than later years anyway; and the sway bars they used in 84 were probably 32mm & 22mm but might have been as small as 21 in the rear, as compared to later years when they were as large as 36mm hollow or 34mm solid in the front & 24mm rear; and of course your end links are all worn out too, but you can go to AutoZone and buy new poly ones that are better than the originals were the day they were installed, for about $15. So other than a trivial historical curiosity, "WS6" doesn't mean a whole lot on cars that old. Speaking strictly from personal experience: my 83 is a "WS6 car", and has all the same weenie things about it, that had to be upgraded as they became available throughout the 80s. Mine got new springs (Moog) in about 88, new poly bushings at about the same time, IROC sway bars (34 & 24) in about 94 or 95, and so on. Each of those things made a HUGE difference in my worn-out old car, starting when it was only 6 or 7 years old. I can only imagine how worn out that stuff must be in yours after 25 years. Time to stop worrying about "WS6" and codes, and start thinking about PARTS.

Don't trust the RPO codes. They only tell you what the car CAME WITH, not what the car HAS NOW. For example, my 83 still has its stock gear (only 3.73 unfortunately), a 91 rear housing, an Eaton posi with 28 spline axles, PBR rear disc brakes (90-up), a 97 T-56, and various other things not shown in the codes. Look at your parts, change your fluid which NEEDS it, and find out what's REALLY there. I hope you actually have what your codes say, and that it's not a Gov-Lock and that it all still works, but there's no guarantee.

 

>>>Thanks a bunch for the info, I appreciate it. My car is an 80k mile survivor, so I suspect it is all original; at least that was the claim from the seller, and I have no reason to doubt it. I have all the repair receipts, and other than fresening up the motor, all the work was minor (brakes, exhaust, etc). Thanks again. This is a great resource site.