Rear Axle Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

71HUGGER396 · 03-01-2009, 01:38 PM

I'm getting ready to start working on my 1970 2wd Blazer. It has 6 Lugs, I was going to keep it that way, but I got a really good deal on everything I needed for the disc swap up front, the new stuff has 5 lug. What's the differance on some of the rear axles? I have a 1972 rear axle, don't won't to use it, it;'s very rusty. The axle housing under the Blazer is very nice. Can I just change axles shafts.

muddobber · 03-01-2009, 01:44 PM

no 71 and 72 axleshafts are longer

sameyrasmea72 · 03-01-2009, 01:50 PM

I was thinking that the axles were longer in 1970.

71HUGGER396 · 03-01-2009, 01:53 PM

According to Early Classics catalog, the 1970 is the same as 1972. That is why I'm asking all the experts on the board.

Longhorn Man · 03-01-2009, 03:42 PM

there is a good chance that the 70 is as long as the 71/72. There was a chainge mid year, it seems to be more of a chainge 1/4 the way through the year since more were wider than narrow.

**Green Machine** · 03-01-2009, 03:43 PM

1970 was a crossover year, some had the narrower rear and some had the wider rear, our 70 has the wider version.

71HUGGER396 · 03-01-2009, 05:01 PM

Can I just measure the housing or do I have to measure the axle shaft? What is the differance between the years?

67_C-30 · 03-01-2009, 05:57 PM

Just measure it from plate to and if it is the same as your '72 rearend, you're good. I know some 70's had the narrow rearend, but of the 6 or so 70's I've owned, all of them had the wide one.

lts70 · 03-01-2009, 10:36 PM

If you have the “wide” rear end your axle will be 58.5" back-plate to back-plate, if you have the shorter rear-end it will be 57”. If you have the axles out the "wide" rear end axle shafts are 31.5" long, the "narrow" rear end axle shafts are 30.75" long.

71HUGGER396 · 03-02-2009, 09:35 AM

Thanks for all you replies.

03-01-2009, 01:38 PM	#1
71HUGGER396 Confirmed Truckaholic Join Date: Oct 2000 Location: Sarver,PA 16055 Posts: 732	Rear Axle Question I'm getting ready to start working on my 1970 2wd Blazer. It has 6 Lugs, I was going to keep it that way, but I got a really good deal on everything I needed for the disc swap up front, the new stuff has 5 lug. What's the differance on some of the rear axles? I have a 1972 rear axle, don't won't to use it, it;'s very rusty. The axle housing under the Blazer is very nice. Can I just change axles shafts. __________________ 1968 50th STEP SIDE SHORTY, 350/350, a/c, ps, p,b Daily Driver, 1970 Cst short fleet, all black, 350/350, 1970 2wd Blazer, 2wd, 6 cyl. 3 spd, original, now a 454, 350turbo, 3.73 posi, on the road 1971 2wd fleet shorty, 454, 700r4, 3.73 posi, SOLD to 67OLDSTYLE72 "My rig's a little old but that don't mean she's slow" - SAWYER BROWN's Six Days On The Road SEMPER FI "I use to be a lean mean fighting machine, but now I'm a huffin, puffin, over stuffin love muffin"

03-01-2009, 01:44 PM	#2
muddobber muddobber Join Date: Dec 2008 Location: lavaca ar Posts: 78	Re: Rear Axle Question no 71 and 72 axleshafts are longer

03-01-2009, 01:50 PM	#3
sameyrasmea72 Senior Member Join Date: Aug 2003 Location: Lubbock, Texas Posts: 2,443	Re: Rear Axle Question I was thinking that the axles were longer in 1970. __________________ 72 Cheyenne Super 80 Silverado Blazer 2wd

03-01-2009, 01:53 PM	#4
71HUGGER396 Confirmed Truckaholic Join Date: Oct 2000 Location: Sarver,PA 16055 Posts: 732	Re: Rear Axle Question According to Early Classics catalog, the 1970 is the same as 1972. That is why I'm asking all the experts on the board. __________________ 1968 50th STEP SIDE SHORTY, 350/350, a/c, ps, p,b Daily Driver, 1970 Cst short fleet, all black, 350/350, 1970 2wd Blazer, 2wd, 6 cyl. 3 spd, original, now a 454, 350turbo, 3.73 posi, on the road 1971 2wd fleet shorty, 454, 700r4, 3.73 posi, SOLD to 67OLDSTYLE72 "My rig's a little old but that don't mean she's slow" - SAWYER BROWN's Six Days On The Road SEMPER FI "I use to be a lean mean fighting machine, but now I'm a huffin, puffin, over stuffin love muffin"

03-01-2009, 03:42 PM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Rear Axle Question there is a good chance that the 70 is as long as the 71/72. There was a chainge mid year, it seems to be more of a chainge 1/4 the way through the year since more were wider than narrow.

03-01-2009, 03:43 PM	#6
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Rear Axle Question 1970 was a crossover year, some had the narrower rear and some had the wider rear, our 70 has the wider version. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0

03-01-2009, 05:01 PM	#7
71HUGGER396 Confirmed Truckaholic Join Date: Oct 2000 Location: Sarver,PA 16055 Posts: 732	Re: Rear Axle Question Can I just measure the housing or do I have to measure the axle shaft? What is the differance between the years? __________________ 1968 50th STEP SIDE SHORTY, 350/350, a/c, ps, p,b Daily Driver, 1970 Cst short fleet, all black, 350/350, 1970 2wd Blazer, 2wd, 6 cyl. 3 spd, original, now a 454, 350turbo, 3.73 posi, on the road 1971 2wd fleet shorty, 454, 700r4, 3.73 posi, SOLD to 67OLDSTYLE72 "My rig's a little old but that don't mean she's slow" - SAWYER BROWN's Six Days On The Road SEMPER FI "I use to be a lean mean fighting machine, but now I'm a huffin, puffin, over stuffin love muffin"

03-01-2009, 05:57 PM	#8
67_C-30 I have a radical idea! Join Date: Jan 2005 Location: Sweet Home Alabama! Posts: 6,513	Re: Rear Axle Question Just measure it from plate to and if it is the same as your '72 rearend, you're good. I know some 70's had the narrow rearend, but of the 6 or so 70's I've owned, all of them had the wide one. __________________ '67 C-30 Dually Pickup 6.2 Turbo Diesel, NP435 ‘72 C-10 SWB , 350 4bbl, TH350 '69 C-10 SWB , 250 L6, 3 OTT '69 GMC C3500, dump truck, 351 V6, NP435 '84 M1009 CUCV Military Blazer 67 C-30 Turbodiesel build thread http://67-72chevytrucks.com/vboard/s...d.php?t=254096 My trucks http://s226.photobucket.com/albums/d...ediafilter=all Member of the 1-Ton Club!

03-01-2009, 10:36 PM	#9
lts70 1970 Daily Driver Join Date: Jun 2007 Location: Glenns Ferry IDAHO Posts: 1,037	If you have the “wide” rear end your axle will be 58.5" back-plate to back-plate, if you have the shorter rear-end it will be 57”. If you have the axles out the "wide" rear end axle shafts are 31.5" long, the "narrow" rear end axle shafts are 30.75" long. __________________ It's not truly yours if you didn't build it yourself or if you don't do your own maintenance.

03-02-2009, 09:35 AM	#10
71HUGGER396 Confirmed Truckaholic Join Date: Oct 2000 Location: Sarver,PA 16055 Posts: 732	Re: Rear Axle Question Thanks for all you replies. __________________ 1968 50th STEP SIDE SHORTY, 350/350, a/c, ps, p,b Daily Driver, 1970 Cst short fleet, all black, 350/350, 1970 2wd Blazer, 2wd, 6 cyl. 3 spd, original, now a 454, 350turbo, 3.73 posi, on the road 1971 2wd fleet shorty, 454, 700r4, 3.73 posi, SOLD to 67OLDSTYLE72 "My rig's a little old but that don't mean she's slow" - SAWYER BROWN's Six Days On The Road SEMPER FI "I use to be a lean mean fighting machine, but now I'm a huffin, puffin, over stuffin love muffin"



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