12 bolt rear end

[snibook7537]

Hello everyone,

I had to put new axel seals in my truck its a 76 chevy custom deluxe with a 250 6cyl and a 4spd with Granny I was just wondering if anyone else has this same rear end as I do. Its a 12 bolt without Posi,  the people at advanced auto said that they DID NOT COME WITH THAT REAR END it MUST be out of something else, I really think it is the original and I know it was possable to get that rear end in 76 but was it an option or did it come with a package deal with the 4spd? The people at auto zone had the gasket further proving my point it was the original rear end but My friend who has 2 of these trucks, one is a 85 GMC with a 305 its got a ton of options, the people who had it before him used it to pull horses and I kinda would think that it would have a heavy duty rear end with the options list his truck has but its only a 10 bolt, his other truck is a 86 Silverado with a stepsie and 4.10's and that too has a ton of options but its a 10 bolt.  I know thats a lot of years off but is the 12 bolt a 4spd thing or an independent option that the truck just got??

Thanks vince

[dunedigger]

I've had a lot of trucks with a 12 bolt.  In fact, the only ones I've had with a 10 bolt is a 86 2wd and my current blazer.  All my 4x4 1/2 tons have had 12 bolts.  My first truck was a 76 with a 12 bolt.  I never believe anything from a parts counter either.

[Flamingbig10]

the truck truck was available till 81

[Irish_Alley]

64-82 it was available lol or at least according to this web site
http://coloradok5.com/axleguide.shtml
i used to work for autozone bout 5 years ago and some coworkers would do the same thing advance did just cause they could find it on the computer. after they piss off the customer i would take there customer and get them what they wanted most the time we or advance would have it. another story from advance is me and a buddy was doing some work on a 01 ford zx3 focus well we needed a rear bearing its pressed in never stopped us before lol. so i called them up the bearing was $54 sent the car owners there to pick it up and a seal they come back with the bearing and say the guy at advance said it doesn't need a seal. we had just taken one out so she calls them back and now they have the whole assembly for $45 thats the drum bearing and seal. now why didn't they say "we have the assembly and its cheaper"

[SUX2BU99]

If it's original, 1/2-ton and your truck is 81-older, it's a 12 bolt. You can actually tell what year the rear end is if you crawl under there and if you are looking at the front of the diff housing, look on the driver side, near where the axle and housing meet. It should say "GM 76" in 1" high letters if it is a 1976 rear end.

[Captkaos]

all 73-80 trucks had 12bolts, 81's are a hit/miss, by 82 10 bolts were the norm as most 12's stock were used up.