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Old 09-03-2015, 10:31 AM   #1
Wizit247
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Help identifying 12 bolt!

So from any of my searches my stamp on my 12 bolt doesnt have as many numbers as it should. can someone more knowledgeable than me decode this? or point me in the right direction.

This is stamped on the passenger axle tube just like it should be. There was only one number cast into the center section. it was tho lower right if seen from the rear. cant remember the number. it started with a G and ended with 55.



Much appreciated!

-Wizit
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Old 09-03-2015, 12:02 PM   #2
GASoline71
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Re: Help identifying 12 bolt!

What are you trying to find out?

If it is limited slip and what ratio?

After 40 years... anything could be in there. Unless you're the original owner of the truck. I'd just pull the cover...

Gary
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Old 09-03-2015, 12:18 PM   #3
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Re: Help identifying 12 bolt!

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Originally Posted by GASoline71 View Post
What are you trying to find out?

If it is limited slip and what ratio?

After 40 years... anything could be in there. Unless you're the original owner of the truck. I'd just pull the cover...

Gary
Mostly just what to tell the kid behind the parts counter what vehicle i need parts for.
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Old 09-03-2015, 12:38 PM   #4
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Re: Help identifying 12 bolt!

http://67-72chevytrucks.com/vboard/s...d.php?t=578793
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Old 09-03-2015, 12:55 PM   #5
Wizit247
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Re: Help identifying 12 bolt!

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thanks..
i guess ill keep searching. my axle doesn't match anything in that thread or the countless others ive been through
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Old 09-03-2015, 01:00 PM   #6
GASoline71
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Re: Help identifying 12 bolt!

If it's a truck 12 bolt... the early ones had 16 spline axles and then the later ones had 30 spline axles. 1971 was when they were widened a tad.

What parts are you looking for?

Gary
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'cuz chicks dig scars...

My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread.

The Rebuild of Creeping Death after the wreck

Quote:
Originally Posted by LONGHAIR View Post
I would never rebuild a 305.
Quote:
Originally Posted by prostreetC-10 View Post
I love using vacuum gauges as part of the carb tuning process. I hook the gauge to the inside of my garbage can and leave it there.
Quote:
Originally Posted by Marv D View Post
Remember Murphys 2nd law of mechanical relationships... "OPPOSING COMPONENTS ATTEMPTING TO OCCUPY THE SAME SPACE, AT THE SAME TIME, GENERALLY END UP OCCUPYING ADJOINING SPACE AT THE BOTTOM OF THE OIL PAN"
Quote:
Originally Posted by cableguy0 View Post
Its cheaper to listen to advice given when you ask for help than it is to ignore everyone and wait for carnage.
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Old 09-03-2015, 01:08 PM   #7
Wizit247
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Re: Help identifying 12 bolt!

Quote:
Originally Posted by GASoline71 View Post
If it's a truck 12 bolt... the early ones had 16 spline axles and then the later ones had 30 spline axles. 1971 was when they were widened a tad.

What parts are you looking for?

Gary
Mostly brakes. potentially diff rebuild.

The diff cover shape is that of a truck axle.

Also, it is 6 lug if that helps any.
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Old 09-03-2015, 01:46 PM   #8
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Re: Help identifying 12 bolt!

what year truck , if its a 68 , ha is a 3.73 open axil , the majority had these
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Old 09-03-2015, 02:08 PM   #9
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Re: Help identifying 12 bolt!

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what year truck , if its a 68 , ha is a 3.73 open axil , the majority had these
unfortunately its not from the truck originally. It came with a frame that I bought.
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Old 09-04-2015, 04:07 PM   #10
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Re: Help identifying 12 bolt!

Just take the cover off. Looks like you are cleaning and painting the outside (lipstick on a pig?). So go ahead and clean out the inside and add to new seals and fluid including limited slip additive if needed.
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Old 09-04-2015, 04:18 PM   #11
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Re: Help identifying 12 bolt!

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Just take the cover off. Looks like you are cleaning and painting the outside (lipstick on a pig?). So go ahead and clean out the inside and add to new seals and fluid including limited slip additive if needed.
As previously stated its not the gearing that Im worried about whatsoever. I need an application to give when buying parts.
If I walk into the parts store and tell them I need brakes for a 12 bolt I will get a blank stare.
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Old 09-05-2015, 06:00 PM   #12
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Re: Help identifying 12 bolt!

Any luck? Here's a bump for you.

Last edited by jdw; 09-05-2015 at 06:01 PM. Reason: Auto correct
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Old 09-07-2015, 05:10 PM   #13
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Re: Help identifying 12 bolt!

The main difference is axle length and 5/6 lug. As stated above splines. If your painting it. take the time pull the cover/measure the axles and housing.You'll know for sure what you have.
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Old 09-07-2015, 08:57 PM   #14
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Re: Help identifying 12 bolt!

A picture of the complete rear end might help narrow down the year. If it's a 2wd truck, They had 2 different track bar mount designs depending on yearly or late. All of our trucks used the 11"x2" brake shoes. 60-63 were different from the 64-72, but that was it. I understand the frustration with going to get parts at the parts store anymore....If they can't look it up in the computer, they are lost! I worked behind the parts store counter when you looked things up in books!
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Old 09-07-2015, 10:12 PM   #15
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Re: Help identifying 12 bolt!

Ring gear will have a date on it if it's original. This is a coil spring truck, correct? They parts should all be the same '66-'72. '63-'65 MAY have some internal differences, I know on the passenger car they first year setup shim pack is different. Can't be any other range than that if a factory coil spring setup.
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