12 bolt rear end width

65sssd · Poncho Master!

12 bolt rear end width

rabbit64cs · Canadian Poncho Superstar!

No, but the internals are the interchangeable

427carl · A Poncho Legend!

Chevrolet

Outside Width	Year	Model
57.75	1962-1964	Chevy II/Nova
57.75	1965-1967	Chevy II/Nova
58.00	1978-1988	Chevy Malibu, Monte Carlo
59.50	1968-1982	Corvette
60.00	1955-1964	Chevy Car
60.00	1967-1969	Camaro
60.25	1968-1979	Chevy II/Nova
60.50	1984-1995	Corvette
60.50	1964-1967	Chevelle
62.00	1955-1959	Chevy Pickup
61.25	1968-1972	Chevelle
62.50	1970-1981

rabbit64cs · Canadian Poncho Superstar!

I believe the Width is 2 inches wider on the b body. I think the control mounting points are differnt as well. Someone here will be able to confirm.

Later... Rog

427carl · A Poncho Legend!

rabbit64cs wrote:

I believe the Width is 2 inches wider on the b body. I think the control mounting points are differnt as well. Someone here will be able to confirm.

Later... Rog

Listed here are backing plate to backing plate rearend lengths for some of the donor Chevrolet vehicles:

1967-'69 Camaro: 60 inches
1964-'67 Chevelle: 61 inches
1968-'72 Chevelle: 62 inches
1965-'70 Chevrolet: 62.4 inches

65sssd · Poncho Master!

Thanks for the info. I had a line on a complete car for cheap. The fact that the rear end is 1.5" wider means it's a no-go. Still on the search for a narrow 12 bolt. Why did I have to pick such a hard car to find parts for??

4SPEED427 · A Poncho Legend!

Boy, a Chevelle/Beaumont 12 bolt for the first models (64-67) is a tough find. Expensive too.

67BBSD · Canadian Poncho Superstar!

Carl Stevenson wrote:

Boy, a Chevelle/Beaumont 12 bolt for the first models (64-67) is a tough find. Expensive too.

theres one advertised locally (Niagara) for $2400

65sssd · Poncho Master!

67BBSD wrote:

Carl Stevenson wrote:

Boy, a Chevelle/Beaumont 12 bolt for the first models (64-67) is a tough find. Expensive too.

theres one advertised locally (Niagara) for $2400

Ouch!!!

67SD396 · Poncho Master!

Correct me if I am wrong but I have always been led to believe that the 1967 Chevelles and Beaumonts had a narrower differential than any other year. Have I been misled now that I see that 64-67 is listed as the same width?

427carl · A Poncho Legend!

67 Chevelle 12 bolt posi CF code 3.31 Positraction rear end - $1500 (Ennis)

Date: 2009-11-22, 3:57PM CST
Reply to: sale-uc6qv-1477821094@craigslist.org ^{[Errors when replying to ads?]}

Rare and complete 67 Chevelle 12 bolt posi CF code 3.31 Positraction rear end from a 4spd '67 SS396.
Fits 64-72 GM A-body but is narrower than 68-72 Preferred upgrade for 10 bolt rear end
Correct for 67 Chevelle or El Camino with big block 396 engine.
Date code is E107 May 10th 1967
Car sat up with no engine or tranny for 30-40 years , so mileage is low. Turns over smooth, Feels good, tight posi, one side has new brakes and studs , other side has no brakes and original studs. Ready to run, came of running driving car. car owner wanted less gear (now 350/th350) and I hooked him up with a 2.73 Posi 12 bolt.

Key words : Malibu SS Chevelle Chevy El Camino Chevrolet Pontiac GTO Lemans Tempest Olds 442 Cutlass Buick Skylark GS

Location: Ennis
it's NOT ok to contact this poster with services or other commercial interests

65sssd · Poncho Master!

Where's this place?

4SPEED427 · A Poncho Legend!

67SD396 wrote:

Correct me if I am wrong but I have always been led to believe that the 1967 Chevelles and Beaumonts had a narrower differential than any other year. Have I been misled now that I see that 64-67 is listed as the same width?

64 to 67 are the same width, yes. However, the 67 rear is unique because of the way the bottom of the coil spring mounts on it.

64-66 have a flat pad for the bottom of the spring and a bolt with a big washer on it holds the bottom coil to the mounting plate on the housing.

67 has kind of a round knob sticking up that pokes through the bottom coil on the spring.

-- Edited by Carl Stevenson on Tuesday 15th of December 2009 09:51:58 PM

4SPEED427 · A Poncho Legend!

And also I am not in agreement with all axle widths listed because 67-69 Camaro and 65-67 Chevelle 12 bolt share the same axle. To me that would say the diffs have to be the same width. Oh, and also 68-70 Nova 12 bolt.

-- Edited by Carl Stevenson on Tuesday 15th of December 2009 10:00:17 PM

rabbit64cs · Canadian Poncho Superstar!

I've heard of guys using the 68-72 in the 64-67, they say they fit, but the upper a-arms are at a bit of a different angle. Spring perches are also different in 66 and older.

later..rog

a post just like the info you want....

http://www.chevelles.com/forums/showthread.php?p=452136A

12-bolt from 1965-1966 will bolt right in...
the 1967 Chevelle rear is also very similar, it just has different spring perches (they still work fine)...

a 12-bolt from 1968-1972 will also bolt right in, but these rearends were about 1-1/2 inch wider overall (3/4 inch each side). All the brackets are in the same location though, so wheel/tire clearance is the only big issue (depending on your current combo).

The 10-bolt can also be built up to handle a good amount of power (particularly if running an automatic trans), but its really about the same cost as the 12-bolt in regards to rebuilding... Only the initial procurement of the 12-bolt would be extra...

in 1972, Chevy came out with the 8.5-inch 10-bolt that is supposed to be stronger than the earlier 8.2 unit... This was only used in the 1972 Chevelles (okay, actually used in 1972 and up, but the 1972 is the only one that is a direct bolt-in for you).

There is also the 9-inch Ford, that many companies are offering to bolt-in to the Chevelles, etc... They are a little more cost-wise than rebuilding the 12-bolt, but you also have to buy the used 12-bolt, and the 9-inch has the axles retained by bearing plates, rather than the C-clips... Of course, the 9-inch usually requires a new driveshaft due to the differing location of the pinion flange...

rabbit64cs · Canadian Poncho Superstar!

on anther note, 68 12 bolts are still out there. I have collected 3 to date. 71 Monte Carlo , 69 Skylark, and a 69 Chevelle. Posi's on the other hard are hard to come by , but $500 gets you a new one there abouts.

65sssd · Poncho Master!

Has anybody put stock 14' steels on a 64-65 chevelle or Beaumont with a 68-72 12 bolt rear end? Does it clear the fender?

ak 67sd · Poncho Master!

Do you have 14" steel wheels on your car now? You would think the narrow steel wheels wouldnt have a problem with the extra 3/4" width... i've been looking for a 67 12 bolt, around $1500 seems to be the going rate, a bit more and i'd expect it to be fully rebuilt... there's been a '68 housing for sale locally for a year for $400... 67 is a single year only diff and the harder one to find, if you do use it you just need to buy 67 springs...

my 10 bolt is making a bit of noise, so i'd rather find a 12 then sink $1000 into mine....

ak

67BBSD · Canadian Poncho Superstar!

65sssd wrote:

Has anybody put stock 14' steels on a 64-65 chevelle or Beaumont with a 68-72 12 bolt rear end? Does it clear the fender?

heres a 67 with a 68 rear end and 15 x 7 rallys

ak 67sd · Poncho Master!

I just read on TC that there are late build 67s with the wider diffs... interesting... 67s have a lot of wheelwell room... i'd think a 7" rim and a 245 tire would just fit with the wider rear...

4SPEED427 · A Poncho Legend!

I would be very surprised if they made any 67s with a 68 diff. I bet they have been changed over the years. The axle shaft is a different length and that wouldn't make any sense.

65sssd · Poncho Master!

ak 67sd wrote:

Do you have 14" steel wheels on your car now? You would think the narrow steel wheels wouldnt have a problem with the extra 3/4" width... i've been looking for a 67 12 bolt, around $1500 seems to be the going rate, a bit more and i'd expect it to be fully rebuilt... there's been a '68 housing for sale locally for a year for $400... 67 is a single year only diff and the harder one to find, if you do use it you just need to buy 67 springs...

my 10 bolt is making a bit of noise, so i'd rather find a 12 then sink $1000 into mine....

ak

I have the original 14's on the car now and that's what I run. I just don't know if a 68-72 will fit in the fenders. I want too keep two rear ends. One with a highway gears and the other with a 4:11. As for the 10 bolts if you keep them a non posi they last but with the posi they go boom.

ak 67sd · Poncho Master!

sometimes you never know... there is a guy on tc claiming to have an original longer axle june built diff in his 67ss... also see this quote from the chevellestuff reference guide...it *may* be true, but who knows!

Casting Numbers:
12-Bolt Casting #N3894939 (narrow early model year), #NF3917124 (wide late model year)*
10-Bolt Casting #3894938N

* (Note: For what it's worth, ALL 67 rear ends I've ever seen were the narrow variety and used the spring cup like 68-72 but were narrower like the 64-66. I do have photos of a June 1967 cast #3917124 rear end but the assembly date is October - obviously for a 1968 model year Chevelle. However, a June 1967 casting date rear end such as this might have found its way into very late 1967 model year Chevelles as well and could be the basis for the statement in an article from Car Craft magazine some years ago titled "Inside 64-72 A-Bodies".)

65sssd · Poncho Master!

67BBSD wrote:

65sssd wrote:

Has anybody put stock 14' steels on a 64-65 chevelle or Beaumont with a 68-72 12 bolt rear end? Does it clear the fender?

heres a 67 with a 68 rear end and 15 x 7 rallys

I wish I had the room of a 67. Mines tight with the stock 10 bolt.

ak 67sd · Poncho Master!

i run a 10 bolt 8.2 posi, with 4:56 gears behind a 450hp sbc on ET street tires (so no tire spin!) for many many years, it does hold up, but after 43 years it wants to be refreshed!!

if you have more than 3/4" clearance per side you'll be able to fit a later style wide rear in there...

ak