Need rearend compatibility info - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**RenoKeene** · 05-07-2013, 09:53 AM

Having trouble finding a local 12 bolt leaf rear for our next 70 GMC build..
I know the width got wider after 70, my concern is saddle and shock mount bracket locations. My question is are any later model rears with brackets in the same locations?
I found a 74 Blazer and a 78 1/2 ton 4x4 in a junk yard but can't get under them to measure.
Any info will help.
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**RenoKeene** · 05-07-2013, 09:29 PM

Anybody? Really don't want to have to take a shovel to the yard.....but I can if I have to.
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andrewmp6 · 05-08-2013, 03:26 AM

If i remember right the 73-87 rear end is 64 and 1/2 inches wide,And yours is 57 inches wide.As far as the brackets in the same place i have no idea on those.

wraprail · 05-12-2013, 07:21 AM

Quote:

Originally Posted by andrewmp6

If i remember right the 73-87 rear end is 64 and 1/2 inches wide,And yours is 57 inches wide.As far as the brackets in the same place i have no idea on those.

Seven and a half inches wider?
Really?

**RenoKeene** · 05-12-2013, 10:40 AM

I believe the 71-72 rears are 59" back plate to back plate. Someone can jump in and correct me if I'm wrong. Later models should be similar I think.
Very surprise no one has answered this yet, maybe I posted this in the wrong spot?
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**oldman3** · 05-12-2013, 11:56 AM

I did a search on site once along time ago and this is what I got back. Not sure if it is
100% correct, but I think it is very close.

67-69 mounting flange to mounting flange = 60"
70-72 mounting flange to mounting flange = 62"
73-87 mounting flange to mounting flange = 63.5"

In parts catalog new 5 lug axle for 63-69 are 30-3/4" long and the 70 5 lug axle is 31-1/2". Doing the math this doesn't add up right for flange to flange, but that's what it shows. Working on a 68 SWB now, that the owner installed a 10 bolt 81 axle and it is 63.5" flange to flange. Hope this doesn't muddy up the water to much....Jim

**oldman3** · 05-12-2013, 12:41 PM

check this thread out it has some good info...Jim http://67-72chevytrucks.com/vboard/s...d.php?t=551752

**RenoKeene** · 05-12-2013, 09:49 PM

Thanks Jim, good info.
Posted via Mobile Device

05-07-2013, 09:53 AM	#1
RenoKeene Florida Edition Join Date: Oct 2010 Location: Fruitland Park, FL Posts: 4,034	Need rearend compatibility info Having trouble finding a local 12 bolt leaf rear for our next 70 GMC build.. I know the width got wider after 70, my concern is saddle and shock mount bracket locations. My question is are any later model rears with brackets in the same locations? I found a 74 Blazer and a 78 1/2 ton 4x4 in a junk yard but can't get under them to measure. Any info will help. Posted via Mobile Device __________________ 70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394

05-07-2013, 09:29 PM	#2
RenoKeene Florida Edition Join Date: Oct 2010 Location: Fruitland Park, FL Posts: 4,034	Re: Need rearend compatibility info Anybody? Really don't want to have to take a shovel to the yard.....but I can if I have to. Posted via Mobile Device __________________ 70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394

05-08-2013, 03:26 AM	#3
andrewmp6 Registered User Join Date: Jan 2009 Location: Louisville,Ky Posts: 5,811	Re: Need rearend compatibility info If i remember right the 73-87 rear end is 64 and 1/2 inches wide,And yours is 57 inches wide.As far as the brackets in the same place i have no idea on those.

05-12-2013, 10:40 AM	#5
RenoKeene Florida Edition Join Date: Oct 2010 Location: Fruitland Park, FL Posts: 4,034	Re: Need rearend compatibility info I believe the 71-72 rears are 59" back plate to back plate. Someone can jump in and correct me if I'm wrong. Later models should be similar I think. Very surprise no one has answered this yet, maybe I posted this in the wrong spot? Posted via Mobile Device __________________ 70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394

05-12-2013, 11:56 AM	#6
oldman3 Senior Member Join Date: Mar 2011 Location: West Plains, Missouri Posts: 7,559	Re: Need rearend compatibility info I did a search on site once along time ago and this is what I got back. Not sure if it is 100% correct, but I think it is very close. 67-69 mounting flange to mounting flange = 60" 70-72 mounting flange to mounting flange = 62" 73-87 mounting flange to mounting flange = 63.5" In parts catalog new 5 lug axle for 63-69 are 30-3/4" long and the 70 5 lug axle is 31-1/2". Doing the math this doesn't add up right for flange to flange, but that's what it shows. Working on a 68 SWB now, that the owner installed a 10 bolt 81 axle and it is 63.5" flange to flange. Hope this doesn't muddy up the water to much....Jim __________________ my build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=459839 Jimbo's long bed step build:http://67-72chevytrucks.com/vboard/s...t=464626<br /> Last edited by oldman3; 05-12-2013 at 12:09 PM.

05-12-2013, 12:41 PM	#7
oldman3 Senior Member Join Date: Mar 2011 Location: West Plains, Missouri Posts: 7,559	Re: Need rearend compatibility info check this thread out it has some good info...Jim http://67-72chevytrucks.com/vboard/s...d.php?t=551752 __________________ my build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=459839 Jimbo's long bed step build:http://67-72chevytrucks.com/vboard/s...t=464626<br />

05-12-2013, 09:49 PM	#8
RenoKeene Florida Edition Join Date: Oct 2010 Location: Fruitland Park, FL Posts: 4,034	Re: Need rearend compatibility info Thanks Jim, good info. Posted via Mobile Device __________________ 70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394



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