12 bolt need help with I.D.
 

the tube is stamped KDC 251.. What's it out of?????
I have pic also

Re: 12 bolt need help with I.D.
 

since it is out of a Chevelle that narrows the choices. Those were used from 1964 - 1972

The 1964 - 1967 were more narrow than the 1968 - 1972. So if someone knows the width of either the early or later, we will have the answer.

Re: 12 bolt need help with I.D.
 

how do you know its out of chevelle?

Re: 12 bolt need help with I.D.
 

It is either out of a Chevelle/Monte Carlo of some vintage, or out of a big car (Impala, Caprice, wagon) because it is set up for a four link and coil springs.

Re: 12 bolt need help with I.D.
 

Housing widths --------backing plate to backing plate
64-67 Chevelle ---61 inches
68-72 Chevelle/Monte Carlo----62 inches
65-70 Big Car----62.4 inches

Comp 387

Re: 12 bolt need help with I.D.
 

upon further review it is probably out of a early model year 1972 el camino/monte carlo/chevelle
KD ---is the gear ratio 2:73
C------is the assembly plant--- Buffalo
251---is the assembly day of the year---September 8, 1971

Comp 387

Re: 12 bolt need help with I.D.
 

forgot to add check the differential casting-- for a 12 bolt it should be 3969278
Comp 387

Re: 12 bolt need help with I.D.
 

"how do you know its out of chevelle?'

I have a good eye for rear ends! [smile]

Re: 12 bolt need help with I.D.
 

The big car 12 bolt doesn't have the ears on the center casting.

Re: 12 bolt need help with I.D.
 

Mark, the one we have does. Well, it did, they were cut off. The Chevelle housing does not have the big inner pinion bearing, or the big carrier bearing saddles. This housing has the big inner pinion bearing and the ears cut off of the top of the center casting, or at least almost all of them are gone. I've seen stock Chevelle and Camaro housings cut for the big carrier bearings, but I've never seen one cut for the big inner pinion bearing. It might have been there on some COPO Chevelles, but those cars were very rare, and I doubt anyone cut one of the housings up like that to fit a Camaro.

Re: 12 bolt need help with I.D.
 

that looks more like the wheel mounting surface (flange to flange) measurements


try not to end up with a truck 12 bolt...;)

Re: 12 bolt need help with I.D.
 

I measured the housing flanges outside to outside and it measures 55 1/4 "

Re: 12 bolt need help with I.D.
 

My source tells me

64-67 is 56 1/2 flange to flange and 60 1/2 outside of brake drum to outside of brake drum
68-72 measurements are/is 58 1/2 and 62 1/2
68 was the transitional year so some early 68 vehicles might have leftover 67 housings

anyway kdc info is still correct--Comp 387

Re: 12 bolt need help with I.D.
 

i measured the welded on flanges that the brake plate bolts too that are on the axle tubes.
i guarantee it's NOT a truck rear.

Re: 12 bolt need help with I.D.
 

55 1/4" is the flange to flange measurement for a 68-72 Chevelle or Monte Carlo housing.

Re: 12 bolt need help with I.D.
 

i've got a 67 chevelle sitting out back of the shop right now BUT it's covered in that white stuff right now.
got a 10 bolt in it though..
how big of a hurry are ya for measurements?or is that even what you need?
i AM surpised at all the chevelle info that's out there, that there isn't any code charts...

Re: 12 bolt need help with I.D.
 

Go to a website CHEVELLESTUFF.COM one of the best out there gives you almost everything you need to know about deciphering GM codes on these cars---Comp 387