Need help with rearend axle swap - The 1947 - Present Chevrolet & GMC Truck Message Board Network

The Big Green · 01-16-2010, 04:21 PM

Well I have a '67 with a 71-72 5lug rearend swap. I have a 4link and it's too hard to cut, align and reweld new brackets on a 6lug rearend. I want 6x5.5 pattern for a better choice of bs wheels. I heard that I can swap backing plates and axles from a 67, which a guy I know has and get my rear 6lug while gaining 3/4in wheel room. Is this true?

**john** · 01-16-2010, 04:41 PM

The 67 axles are shorter than 71-72's Some 1970 models have the longer six lug axles,

The Big Green · 01-16-2010, 04:47 PM

Yes, I know that the 71-72 are 1.5in wider. I heard that swapping my axles and backing plates for 67-70 ones and making it 6lug and also 1.5in narrower than I am now.

**john** · 01-16-2010, 05:03 PM

You still have the longer 71-72 housing. Sometime during the 1970 year gm went to the same housing as 71-72. Without custom axles , the1970 six lugs are the only bolt in's that will work. Some people have used the later backing plates and drums to use 71-72 axles in the early shorter housings.

cdowns · 01-16-2010, 05:05 PM

the shorter axels dont fit in the longer housings it doesnt matter what backing plates you use
THEY DONT FIT

Zeke · 01-16-2010, 06:05 PM

Would 71-72 4x4 axles fit? They stayed 6 lug.

**lolife99** · 01-18-2010, 12:12 AM

Quote:

Originally Posted by The Big Green

Yes, I know that the 71-72 are 1.5in wider. I heard that swapping my axles and backing plates for 67-70 ones and making it 6lug and also 1.5in narrower than I am now.

No.
This is incorrect.

The Big Green · 01-18-2010, 03:51 AM

Will 73+ 4x4 axles fit? Heard that too lol.

Basically what are my options here? I need 6lug and I need higher than my 4.11 gears. I'd have someone cut the brackets and install a different rearend but I just don't really know. I could redrill the pattern if I can but in a way that 3/4in would be a nice little gain.

Zeke · 01-18-2010, 08:04 AM

Pretty sure 70-81 4x4 would fit. 0.031 shouldn't make a difference

http://www.drivetrain.com/parts_cata...s.html#GMTRUCK

14071750
70-81 BLAZER, JIMMY, SUBURBAN, PICKUP, 1/2-TON 31-9/32'
6 Lug
30 spline
8.875"
$130.23

14071751
71-81 BLAZER, SUBURBAN AND PICKUPS 31-5/16"
5 Lug
30 spline
8.875"
$130.23

01-16-2010, 04:21 PM	#1
The Big Green Registered User Join Date: Oct 2007 Location: Fort Smith,AR Posts: 1,305	Need help with rearend axle swap Well I have a '67 with a 71-72 5lug rearend swap. I have a 4link and it's too hard to cut, align and reweld new brackets on a 6lug rearend. I want 6x5.5 pattern for a better choice of bs wheels. I heard that I can swap backing plates and axles from a 67, which a guy I know has and get my rear 6lug while gaining 3/4in wheel room. Is this true?

01-16-2010, 04:41 PM	#2
john member #16 Join Date: Dec 1999 Location: Yuba City Ca. Posts: 3,618	Re: Need help with rearend axle swap The 67 axles are shorter than 71-72's Some 1970 models have the longer six lug axles, __________________ john http://67-72chevytrucks.com/vboard/showgroups.php board vendors http://www.flickr.com/photos/1745471...7602865984234/

01-16-2010, 04:47 PM	#3
The Big Green Registered User Join Date: Oct 2007 Location: Fort Smith,AR Posts: 1,305	Re: Need help with rearend axle swap Yes, I know that the 71-72 are 1.5in wider. I heard that swapping my axles and backing plates for 67-70 ones and making it 6lug and also 1.5in narrower than I am now.

01-16-2010, 05:03 PM	#4
john member #16 Join Date: Dec 1999 Location: Yuba City Ca. Posts: 3,618	Re: Need help with rearend axle swap You still have the longer 71-72 housing. Sometime during the 1970 year gm went to the same housing as 71-72. Without custom axles , the1970 six lugs are the only bolt in's that will work. Some people have used the later backing plates and drums to use 71-72 axles in the early shorter housings. __________________ john http://67-72chevytrucks.com/vboard/showgroups.php board vendors http://www.flickr.com/photos/1745471...7602865984234/

01-16-2010, 05:05 PM	#5
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Need help with rearend axle swap the shorter axels dont fit in the longer housings it doesnt matter what backing plates you use THEY DONT FIT __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

01-16-2010, 06:05 PM	#6
Zeke Active Member Join Date: Jun 2002 Location: L.A. Lower Alabama Posts: 453	Re: Need help with rearend axle swap Would 71-72 4x4 axles fit? They stayed 6 lug. __________________ 1969 C10 350 3spd 1995 GMC 3500 XC 350 dually When Thomas Edison worked late into the night on the electric light, he had to do it by gas lamp or candle. I'm sure it made the work seem that much more urgent. George Carlin

01-18-2010, 03:51 AM	#8
The Big Green Registered User Join Date: Oct 2007 Location: Fort Smith,AR Posts: 1,305	Re: Need help with rearend axle swap Will 73+ 4x4 axles fit? Heard that too lol. Basically what are my options here? I need 6lug and I need higher than my 4.11 gears. I'd have someone cut the brackets and install a different rearend but I just don't really know. I could redrill the pattern if I can but in a way that 3/4in would be a nice little gain.

01-18-2010, 08:04 AM	#9
Zeke Active Member Join Date: Jun 2002 Location: L.A. Lower Alabama Posts: 453	Re: Need help with rearend axle swap Pretty sure 70-81 4x4 would fit. 0.031 shouldn't make a difference http://www.drivetrain.com/parts_cata...s.html#GMTRUCK 14071750 70-81 BLAZER, JIMMY, SUBURBAN, PICKUP, 1/2-TON 31-9/32' 6 Lug 30 spline 8.875" $130.23 14071751 71-81 BLAZER, SUBURBAN AND PICKUPS 31-5/16" 5 Lug 30 spline 8.875" $130.23 __________________ 1969 C10 350 3spd 1995 GMC 3500 XC 350 dually When Thomas Edison worked late into the night on the electric light, he had to do it by gas lamp or candle. I'm sure it made the work seem that much more urgent. George Carlin Last edited by Zeke; 01-18-2010 at 08:06 AM. Reason: added 2wd info



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