Rear end width change?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

brawley · 08-22-2014, 02:05 PM

I thought I remember hearing that in 1970 they widened the rear end 1 1/2" wider than the 67-69 models, anyone know if this is true?? thanks

**LockDoc** · 08-22-2014, 02:11 PM

Quote:

Originally Posted by brawley

I thought I remember hearing that in 1970 they widened the rear end 1 1/2" wider than the 67-69 models, anyone know if this is true?? thanks

Yes it is, 3/4" on each side. I think it was '71 though....

Someone will correct me if I'm wrong on the year.

LockDoc

Coley · 08-22-2014, 02:20 PM

Full agreement with LockDoc's comments....it was widened in '71.
I believe the reason for this was that they introduced disc brakes onto the trucks in '71 and this disc brake assembly was wider than the previous front drum brakes.
Again, to my understanding....they then made sure the rear track had the same width as the front.
Like Lockdoc also said,....someone correct me if I'm wrong on this.

Coley

**michael bustamante** · 08-22-2014, 02:16 PM

70 model c10 came wiith both 67-69 and 71-72 length rear ends but they are ALL 6 lug still. I have a long length 70 rear end 6 lug under my trailer

**NC67Chev** · 08-22-2014, 02:26 PM

Quote:

Originally Posted by michael bustamante

70 model c10 came wiith both 67-69 and 71-72 length rear ends but they are ALL 6 lug still. I have a long length 70 rear end 6 lug under my trailer

Agree with Michael. I just put a wide 6 lug rear end from a '70 on my '67. I actually think some late '69's got the wide ones too.

70shortstep · 08-22-2014, 06:23 PM

My 70 has the wide rear end.

Wizo · 08-22-2014, 06:42 PM

i had heard this also. Then it dawned on me that i had had a 71 rear end overhauled for my 68 short step side.Now i think my wheels and tires are going to stick out. Anybody ever shortened the axel tube and then put in shorter inner axels? Is it possible to buy shorter inner axels? I could just put the 68 axel back in but i spent good $$$$$$ to have this one overhauled and turned into a 3.73 posi. many thanks in advance.

**NC67Chev** · 08-22-2014, 07:12 PM

Quote:

Originally Posted by Wizo

i had heard this also. Then it dawned on me that i had had a 71 rear end overhauled for my 68 short step side.Now i think my wheels and tires are going to stick out. Anybody ever shortened the axel tube and then put in shorter inner axels? Is it possible to buy shorter inner axels? I could just put the 68 axel back in but i spent good $$$$$$ to have this one overhauled and turned into a 3.73 posi. many thanks in advance.

Does your '68 still have drum brakes? If so, I think your front and rear will be about the same width after the '71 rear is added. If you've upgraded to disc brakes, I think the front will still be wider than the rear...even with wider rear end.

**too much stuff** · 08-22-2014, 09:12 PM

I believe 70 was the change over. Early 70s were narrow.

Wizo · 08-23-2014, 11:09 AM

Too much stuff; Yes its wider because i measured it against the 68.
NC67Chev: My truck has 71 disc breaks. I cut the 71 frame off just before the vin # underneath the cab and grafted it to my 68 frame. this way i can retain the original vin# of the 68. I would really to use 295/50R/15's out back and still get them inside the fender. shortening the axel is no problem. i just was wondering if i can get shorter inner axels. Tks

**70CHEVYBB** · 08-24-2014, 12:26 PM

does anyone have the dimentions of both? axle flange to axle flange

Thanks, Wes

volksworld · 08-25-2014, 09:01 AM

my leaf spring 70 was the wide one...when the ring and pinion went bad,i put in a 76 rear...and the 70 6-lug axles went right in

**kitsbeach** · 10-13-2014, 06:26 PM

Quote:

Originally Posted by 70CHEVYBB

does anyone have the dimentions of both? axle flange to axle flange

Thanks, Wes

I'm interested in this too because I want to order conversion axles for my '67 but want to make sure I still have the narrower diff installed.

Mine is 57" from backing plate to backing plate (at the bend in the tape. It's not that obvious in the picture).

BarryV · 12-17-2014, 07:12 PM

Quote:

Originally Posted by 70CHEVYBB

does anyone have the dimentions of both? axle flange to axle flange

Thanks, Wes

Reviving an old thread ...

I didn't find an answer to this question from Wes. I want to order axles BEFORE I take them out of my 1970 GM corporate 12 bolt. I am preparing for the holidays ... Merry Christmas ... and don't have time to take it apart at the moment.

How do I know if I have the shorter or the wider rear end? I will measure mine and post it later.

Thanks in advance,

Barry

**70CHEVYBB** · 12-17-2014, 07:54 PM

I bought my new dorman axles that have bearings with them for 102.00 an axle free shipping on ebay. outside of flange to end of axle is 31 5/16 . dorman number is 630-128 this is for the wider of the two rear axles.

BarryV · 12-17-2014, 08:11 PM

Quote:

Originally Posted by 70CHEVYBB

I bought my new dorman axles that have bearings with them for 102.00 an axle free shipping on ebay. outside of flange to end of axle is 31 5/16 . dorman number is 630-128 this is for the wider of the two rear axles.

Thanks for that info. I was looking at that one earlier today.

Looks like my question was not stated correctly (or at least it was stated poorly!).

How can I tell if I have the narrow axle HOUSING or the wider axle HOUSING without removing the axle SHAFT and measuring it?

Thanks!

Barry

BarryV · 12-17-2014, 08:26 PM

Mine is 57" from flange to flange, not counting the width of the flange. I am calling the flange the place where the backing plate attaches.

Barry

**70CHEVYBB** · 12-18-2014, 09:37 AM

axle width is 55.5 wide with 30.5 long axles on the narrow rear end. earlier rear end
axle width is 57 wide with 31 5/16 long axles on the wider rear end. later rear end

BarryV · 12-18-2014, 12:05 PM

Quote:

Originally Posted by 70CHEVYBB

axle width is 55.5 wide with 30.5 long axles on the narrow rear end. earlier rear end
axle width is 57 wide with 31 5/16 long axles on the wider rear end. later rear end

Thank you Wes! Got mine ordered today.

Barry

**kitsbeach** · 12-25-2014, 12:48 AM

Quote:

Originally Posted by 70CHEVYBB

axle width is 55.5 wide with 30.5 long axles on the narrow rear end. earlier rear end
axle width is 57 wide with 31 5/16 long axles on the wider rear end. later rear end

Where you measuring from..axle flange or backing plate.?

Mav · 10-11-2023, 02:09 PM

Have late build 70 K10, (7-10-70) Janesville Wi. Rear is 1 1/2 inches narrower than front.

**'68OrangeSunshine** · 10-11-2023, 05:16 PM

I found this out when I cannibalized the '67 rear-end from my '67 K/10 Suburban for my '71 GMC K/1500 Jimmy. Both were 3.73.
The shorter '67 rear [w/ Auburn Posi] was shoe-horned onto my '71 Jimmy. Running very nicely since 2010.
The wider OEM '71 Eaton Posi rear which ''lunched'' is currently hanging under the '67 Sub, but we were unable to fit it completely on. There's some baling wire involved. Not a problem as the Sub is not a runner. It's a Someday Project.
To resurrect the Sub, I would have to get the Eaton Posi rear rebuilt, then trade it out onto the Jimmy, and having pulled the Auburn Posi rear off the Jimmy, ire-nstall it on the Sub.
Not happening anytime soon.

custom10nut · 10-12-2023, 05:16 PM

Following, mainly because I’m about to get a donor rear end to convert it to Posi and Disc Brakes.

Mav · 10-12-2023, 05:59 PM

Envy the brakes, but not enough to do it. lol And the donors around here are parked out by the barn, (gonna fix it up someday)

**58 Special** · 10-12-2023, 08:17 PM

Had worn axles on my 71 K10 suburban.
I had installed cheater bearings.
When wreaking a 70 C10 suburban Axels were exactly the same.

08-22-2014, 02:05 PM	#1
brawley Easy Does It Join Date: Apr 2007 Location: Dirdy Mo , North Carolina Posts: 450	Rear end width change?? I thought I remember hearing that in 1970 they widened the rear end 1 1/2" wider than the 67-69 models, anyone know if this is true?? thanks

08-22-2014, 02:20 PM	#3
Coley Registered User Join Date: Oct 2011 Location: Victoria, B.C Posts: 3,794	Re: Rear end width change?? Full agreement with LockDoc's comments....it was widened in '71. I believe the reason for this was that they introduced disc brakes onto the trucks in '71 and this disc brake assembly was wider than the previous front drum brakes. Again, to my understanding....they then made sure the rear track had the same width as the front. Like Lockdoc also said,....someone correct me if I'm wrong on this. Coley __________________ ....for some men, there is experience, skill and effort....for the others...there is visa and UPS LOL 1966 Chevy 1/2 ton (Florida- Red/white) 1972 Chevy 1/2 ton (California- Blue/white) 2005 Chevy Silverado HD2500/Duramax 2000 Dodge Ram 1500

08-22-2014, 02:16 PM	#4
michael bustamante Senior Member Join Date: Sep 2007 Location: Albuquerque NM Posts: 7,862	Re: Rear end width change?? 70 model c10 came wiith both 67-69 and 71-72 length rear ends but they are ALL 6 lug still. I have a long length 70 rear end 6 lug under my trailer __________________ 1967custom

08-22-2014, 06:23 PM	#6
70shortstep Registerd User Join Date: Nov 2006 Location: Little Rock,AR Posts: 220	Re: Rear end width change?? My 70 has the wide rear end. __________________ John My build thread http://67-72chevytrucks.com/vboard/s...d.php?t=613398

08-22-2014, 06:42 PM	#7
Wizo Registered User Join Date: Dec 2012 Location: Tacoma WA Posts: 274	Re: Rear end width change?? i had heard this also. Then it dawned on me that i had had a 71 rear end overhauled for my 68 short step side.Now i think my wheels and tires are going to stick out. Anybody ever shortened the axel tube and then put in shorter inner axels? Is it possible to buy shorter inner axels? I could just put the 68 axel back in but i spent good $$$$$$ to have this one overhauled and turned into a 3.73 posi. many thanks in advance.

08-22-2014, 09:12 PM	#9
too much stuff Roadtrip! Join Date: Feb 2003 Location: Grand Rapids MN Posts: 13,786	Re: Rear end width change?? I believe 70 was the change over. Early 70s were narrow. __________________ 67 gmc custom lwb dakota truck. Sold...And bought back 69 swb 4x4 project (in progress) 70 c-10 lwb texas truck 70 4x4/BB/bkts/posi/tach(retired) 70 swb (wifes) 70 jimmy camper 71 K-5 factory 2wd 71 cheyenne 4x4/tach/posi/ plow rig 71 Cheyenne20 BB, buckets, tach, tilt, 4 speed 72 jimmy CST wyoming rig 72 jimmy Colorado rig 72 lifted texas 4x4 3/4 ton burb 65 fury conv. 383/auto 65 chrysler 300 "L" 413 auto

08-23-2014, 11:09 AM	#10
Wizo Registered User Join Date: Dec 2012 Location: Tacoma WA Posts: 274	Re: Rear end width change?? Too much stuff; Yes its wider because i measured it against the 68. NC67Chev: My truck has 71 disc breaks. I cut the 71 frame off just before the vin # underneath the cab and grafted it to my 68 frame. this way i can retain the original vin# of the 68. I would really to use 295/50R/15's out back and still get them inside the fender. shortening the axel is no problem. i just was wondering if i can get shorter inner axels. Tks

08-24-2014, 12:26 PM	#11
70CHEVYBB Senior Member Join Date: Feb 2012 Location: chillicothe, illinois Posts: 690	Re: Rear end width change?? does anyone have the dimentions of both? axle flange to axle flange Thanks, Wes

08-25-2014, 09:01 AM	#12
volksworld Registered User Join Date: Apr 2011 Location: formerly NY currentlyNC Posts: 390	Re: Rear end width change?? my leaf spring 70 was the wide one...when the ring and pinion went bad,i put in a 76 rear...and the 70 6-lug axles went right in __________________ 1970 short step c10 leaf spring 454

12-17-2014, 07:54 PM	#15
70CHEVYBB Senior Member Join Date: Feb 2012 Location: chillicothe, illinois Posts: 690	Re: Rear end width change?? I bought my new dorman axles that have bearings with them for 102.00 an axle free shipping on ebay. outside of flange to end of axle is 31 5/16 . dorman number is 630-128 this is for the wider of the two rear axles.

12-17-2014, 08:26 PM	#17
BarryV Registered User Join Date: Sep 2014 Location: Corvallis, OR Posts: 40	Re: Rear end width change?? Mine is 57" from flange to flange, not counting the width of the flange. I am calling the flange the place where the backing plate attaches. Barry

12-18-2014, 09:37 AM	#18
70CHEVYBB Senior Member Join Date: Feb 2012 Location: chillicothe, illinois Posts: 690	Re: Rear end width change?? axle width is 55.5 wide with 30.5 long axles on the narrow rear end. earlier rear end axle width is 57 wide with 31 5/16 long axles on the wider rear end. later rear end

10-11-2023, 02:09 PM	#21
Mav Registered User Join Date: Jun 2016 Location: Richland Or. Posts: 115	Re: Rear end width change?? Have late build 70 K10, (7-10-70) Janesville Wi. Rear is 1 1/2 inches narrower than front.

10-11-2023, 05:16 PM	#22
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,504	Re: Rear end width change?? I found this out when I cannibalized the '67 rear-end from my '67 K/10 Suburban for my '71 GMC K/1500 Jimmy. Both were 3.73. The shorter '67 rear [w/ Auburn Posi] was shoe-horned onto my '71 Jimmy. Running very nicely since 2010. The wider OEM '71 Eaton Posi rear which ''lunched'' is currently hanging under the '67 Sub, but we were unable to fit it completely on. There's some baling wire involved. Not a problem as the Sub is not a runner. It's a Someday Project. To resurrect the Sub, I would have to get the Eaton Posi rear rebuilt, then trade it out onto the Jimmy, and having pulled the Auburn Posi rear off the Jimmy, ire-nstall it on the Sub. Not happening anytime soon. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 10-12-2023 at 06:17 PM.

10-12-2023, 05:16 PM	#23
custom10nut Registered User Join Date: Apr 2015 Location: East Tn (In the heart of the Smoky Mtns) Posts: 1,887	Re: Rear end width change?? Following, mainly because I’m about to get a donor rear end to convert it to Posi and Disc Brakes.



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10-12-2023, 05:59 PM	#24
Mav Registered User Join Date: Jun 2016 Location: Richland Or. Posts: 115	Re: Rear end width change?? Envy the brakes, but not enough to do it. lol And the donors around here are parked out by the barn, (gonna fix it up someday)

10-12-2023, 08:17 PM	#25
58 Special Junior Member Join Date: Apr 2023 Location: Edmonton,Alberta, Canada Posts: 83	Re: Rear end width change?? Had worn axles on my 71 K10 suburban. I had installed cheater bearings. When wreaking a 70 C10 suburban Axels were exactly the same.

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