maniehau

Searching for a 12 bolt rear end for my 1979 H/O.
Preferably would like to purchase somewhere in the western USA.
I live in Phoenix, AZ

I'm putting a warmed over 425 BBO in the car. Thanks!

Gerald Nickels

Going to be looking for a long time as they never made one.

CRUZN 66

Your 79 H/O is an A-Body, and to the best of my knowledge they never came with a 12 bolt rear.... Not sure what changes would be required to actually install a G-Body 8 1/2 rear into your 79, but it may be an option...

HighwayStar 442

It may be a G body under there, GM change the A to G rear wheel drive. And give the A body to the new front wheel drives. I believe.


Fifth generation Platform A-body (1978–1981) G-body (1982–1987)

jmcghee

78 to 88, A and G body rears are a dirrect interchange. Moser will build you a 12 bolt diff that will bolt in. The will also buid , a bolt in 9" ford, JD Race can build you an 8.5 bolt in. He is a member here . Jims user name, is Monzaz.

HighwayStar 442

I ordered this one for my 87. New engine with be about 650HP with no power adder. . https://www.strangeengineering.net/p...-package.html/

ROCKETMAN269V

I sold the 8.5" type "O" rear end ( 4.66:1 with a spool ) out of our '72 Cutlass Stock Eliminator car to a guy with a G-body Monte Carlo. Someone makes custom upper control arms for such a swap; I can't remember who at the moment. I bought a rear disc brake kit from The Right Stuff and installed that also. It was a bolt-in operation. The A-body rear is a little wider but not a major issue, if that's what you want.

matt69olds

Southside machine use to make control arms to fit the A body rearend into a Gbody. UMI and other suspension companies still make them

From what I understand, the lower mounts are the same. It’s the upper arms that won’t fit. Either the spacing or angles are different.

joe_padavano

Once you find the out-of-production southside arms, find a too-wide A-body 12 bolt (priced one lately?), and then buy new wheels with the offset you need to make it fit, you're money WELL ahead to buy a purpose-built G-body 9" or 12-bolt.

maniehau

I realize the car never came with a 12 bolt. Everyone knows that. I am merely looking for one if someone already had one for this car they wanted to sell.

I believe in helping out fellow racers BEFORE helping out a company.

Thank you.

maniehau

Thank you very much for your post. I am looking at different rears for this car. It has been brought to my attention that the 12 bolt is more efficient, just as strong and weights less.
I really appreciate your help. If I can help out a fellow member I would like to do that first. If not, I will most likely purchase this package from Strange.

Thanks, Mike

joe_padavano

Fair enough, but we get LOTS of questions like this where the OP doesn't have a clue. If, for example, you had written something like "looking for a 12 bolt converted to fit a G-body" then it would have eliminated much of the static from the responses since it would be obvious you knew what you were talking about. Good luck with the search.

11971four4two

What
ONLY 10 bolts on the cover

FAB 9

HighwayStar 442

S60 HAS A 9.750 inch ring gear. Take that ''FAB 9'' Friends with some Old's racers. All have the S60. With Helical Gear Differential. I added that to mine.

matt69olds

I paid 75 bucks for the 12 bolt in my car. Of course, that was back in 1990. I’m guessing the price has gone up since then. 😁

I agree, 12 bolts are expensive and hard to find. But the 8.5 A body rearend is plentiful and almost as strong. A friend of mine ran one for years in a low 9 second 73 Camaro, still had the factory gears with a spool. He did have aftermarket axles.

I personally have never done a A body rearend into a G body, but I know several people who have. I suppose if you had the rearend, and needed to buy wheels/tires anyway, it wouldn’t be too expensive to make the swap.

maniehau

Interesting to me about the 10 bolt 8.5. This maybe a very easy, inexpensive route here with a motor which will only put out about 450-470hp and most likely not more than 540tq. Does anyone know of anyone who might have a 8.5 out of a G-body (I realize my car is technically an A body, prior to 1982). This would bolt in and give a 3.73 with a limited slip rear diff.

ROCKETMAN269V

Apparently, you haven't priced an 8.5" G-body rear. They are getting harder to find and very pricey.

maniehau

Ha, no I have not.
There might just not be an inexpensive way out of this is what I'm starting to hear.

jmcghee

JD Race built an 8.5 for me It is a bolt in for 78 to 88 A and G bodies. The rear is the same, for A and G . 373 limited slip incloded new upper contol arms and shipping was under $2000 His member name is Monzaz All new, set up by a man , who has been building diffs for a living for years. Used rears run aroun $1500 and then you dont know what you are getting. Im cheap, this is your least expensive route

maniehau

Thank you for the heads up on the 8.5. I will be in contact this morning. Sound advice, much appreciative.

joe_padavano

Yeah, just a touch... And yeah, this is ASKING price, but they don't sell for a lot less than this.

Fun71

Same here, bought a 3.55 posi rear for $75, then years later sold it back to the guy for the same price. Ah, the good old days.

At some point I started stockpiling rearends and currently have this lineup.

maniehau

Fun 71. Your in Phoenix, I'm in Phoenix. How about selling me one of those 12 bolts? I need one for a 1979 A body H/O. Got anything? Mike

Fun71

FYI, those are O-Type rearends which are 12 bolt cover, 10 bolt ring gear, limited parts availability, and expensive parts. Better to go with an 8.5" 10 bolt rear that is just as strong, has a lot more aftermarket support, parts are readily available, and are relatively inexpensive.

brownbomber77

Cheap and plentifulMustang 8.8 swap.

94-04 solid axle from GT or Cobra (Craigslist)($300)

drill guide to change bolt pattern

(https://www.hellsgatehotrods.com/pro.../drill-guides/)

Spherical bearings for the upper housing bushings (eBay)($76)

Adjustable upper control arms (eBay)($126)

Adapter U-joint (3-3130DL) ($9) Rockauto

Driveshaft flange (2-2-939) ($32 Summit)

Cut off old spring perches and weld them on the new rear end

Trick instant center brackets and hardware


I also sell a swap kit with new axles for the 79-98 Mustang 8.8 axles

newmexguy

Assuming you have tried:
www.maliburacing.com
www.gbodyforum.com
Both are heavily populated by racer types, I tried to sell Malibu parts for years on the first one, but it simply not a place where members restore cars. Rather they gut them and set them up for drag strip action. As for the "commonality" of the G body 8.5, I've never seen one in a yard, they weren't installed in the more common Monte Carlo and Malibus, but on the more upscale, lower production BOP G body specialty coupes. And most of those BOP cars did have the standard 7.5 in rear end, just a few had the 8.5's. And I've been going to southwestern pick a parts for over twenty years. Likely there are also numerous FB groups also, where parts can be found.