I picked this up in a junkyard this weekend. It measured nearly ideal dimentions for putting in a thirdgen, and it's certainly beefy, so I decided to risk snagging it even tho I dunno what the hell it is. The fact that it was $45 helped my decision

I found it under a 72 cadillac. Is it just a screwy looking version of a Chevy 12 bolt? a BOP rear? Something specific to Cadillac? Anyone know any specs on it or how strong it is? Are there any parts for it available?

 

It "might" be a Dana 60 diff but I'm not sure if GM used them. I can't find anything specific in my manuals but the axles should be held in by the retainer plates on the ends like a ford 9".

 

Hmmm, Nope. The Dana 60 is only 10 bolt. A Dana 28 is 12 bolt but isn't that shape. The rear cover almost looks like a 12 bolt truck diff. What gets me is that pinion support.

 

The Dana 60 only has 10 bolts. Almost all the danas do. The dana 28 has 12...but the pattern is different.

 

lol whoops...beat me to it.

 

Didn't the Cadillacs back then have some kind of strange traction control rear end or something?

 

Yeah they sure did. It was called the 7500lb curb wieght lol.

Seriously tho I dunno. I havn't pulled the cover off yet, but the wheels spin in opposite directions like an open rear.

 

I'll tell you what it ISN'T... they had a 9 3/8" diff back then, but it is like the Ford 9"--carrier bolts in from the front.

It sure looks weird, I dunno what it is. Pinion gear looks REALLY low in the housing.

 

dana's had the plug in the rear cover too.

 

I took off the cover and a drum, found some more things out.

-the ring gear is 9 1/4 or 9 3/8, hard to tell exactly with it in the case.
-It has no C clips, the axles bolt in at the flange like a 9".
-The pinion has a bolt in pinion support in the front, but it also has a roller bearing around the tip of it that goes into part of the case by the carrier. I guess it's not moving anywhere.
-The differential is open, pretty standard looking. The gears are 3.15s, and have a cadillac stamp on them.

 

Looks like an 8.875" 12 bolt.
available in cars and trucks.

 

I read that a minute ago and I'm still laughing my F#%*@! **** off! (SO bad I can't even freakin' type.)

Yeah, but that 7,500 was only on the rear end.

It's a Saginaw axle, and you'll never break it with a small block.... well, maybe with a 10,000 RPM clutch dump. You should find what is left of an I.D. tag on the input pinion housing flange (on the front side of the axle). You might be able to get info that way, but once you open it up the ratio will become apparent.

The pinion gear is bigger than the ring gear on many smaller axles, and the spider gears are bigger than most pinions you'll see. The axles are fraggin' massive.

When you open it up, you'll find that it not only has the two tapered rollers on the pinion shaft, but a third, straight roller bearing on the end for added support. The carrier position is adjusted side-to-side by nuts instead of shims. It's a nice setup. It's also probably NOT a posi axle, and I don't know if you can still get the cones, springs, and side gears necessary to convert it.

It's all-American beef, for sure. If you can fit it and stand the extra mass, go for it. With the right drive shaft and SFCs, you'll be ready for that 502 big-block. Most of these landed behind the 500-inch Caddies, and while not known for a lot of HP, developed an honest 400 ft/lb plus from just above high idle to 4,500 RPM. They NEEDED a rear end this massive on such a heavy car with that kind of torque, unless it was delivered with the old F78-15 whitewalls (anyone remember that measurement system?)

 

Yes, I remember it, but I wouldn't exactly call it a "measurement", or for that matter, even a "system".

 

remember it, hell i'm still trying to learn what the hell all the new stuff means with tires sizes.

 

Dude - I'm still laughing at your "Cadillac traction control" sheot. I know I'm gonna wake up in the middle of the night and just bust out laughing, and my wife's gonna think I'm even more strange that she thought before.

What kind of clapped-out POS beater of a tank did you get that thing from? Damn! They oughtta recycle that thing into a couple of warships or something.

And what's even more strange, that's just about the time that the Datsun B-210s started showing up. Imagine those little POS tin cans tangling with a 22' long friggin' behemoth of a Sedan DeVille or Biarritz. Even the FWD Eldorado came in at 21' long and just under 5,000 lbs. Man, that would be like hitting some of those big summertime mosquitoes in norhtern Wisconsin and Michigan. I think I'd crap on myself if I were sitting in an old Datsun and saw an LD come cruising up in both outside mirrors - ONE car! I had a girlfriend whose parents had a brand new '73 Eldorado. Sitting in the front seat and looking out over the hood was like looking across Nebraska. And I used to think Corvette hoods were long...

 

Yup, thats the rear.
it is frigg'n massive At least now I know it's made by Saginaw, that should be of some help in finding parts. Do you know what it's commony called? Saginaw 12 bolt, Saginaw 9 3/8"...etc?

And do you know anywhere that would still carry a gear set and a posi/locker carrier for it?

 

Jester,

Look closely at the front side of the right (passenger) axle tube. Get out your handy wire brush and clean the area about 3" to the right of th ecenter housing. You should find about 8 characters there. I'm guessing that they will be something like "WC D ### XX". just fill in the blanks.

The good news is that there were definitely posi carriers for those axles. The question is, where the hell do you find them 30 years later?

 

F78-15 is what, about a 205/70 or 205/75R15. I see some 'farm' trailers with those old sizes once in a while. At my previous job, they had a conversion chart
"Controlled differential" is what they called them back then.
talk about torque, 410 'net' at 2400 rpm with the 500 cube engine. Finding a working posi for it will probably be difficult. However, if you are building an ultra-cheap weekend drag car, you could weld up the spiders, but 3.15's aren't a real good ratio and that was probably about the best offered.

That rear, the caddy 500 cube engine, th400, a little chevy vega.... hmmm.