Sorry if this has been beat to death but my head is spinning and I seem to be getting different answers.:(

Are there any differences in the mounting ear locations or sizes between Chevy 12-bolt rearends for coil spring cars? I'm NOT comparing a BOP to a Chevy. I just need to know if all Chevy 12-bolts have the exact same mounting ear location, lateral angles, and bushing sizes?
If there are different ones can you tell me what years are different and what the differences are?

Greatly appreciate all info on this subject!
Regards
Kevin Slaby

Yes there are differences between the mounting points for various car body types, even though they are all using coil springs. Need to stay with an A-body axle.

Yes there are differences between the mounting points for various car body types, even though they are all using coil springs. Need to stay with an A-body axle.

Just to further clarify, Only the Chevelle and Impala (full size) used 12-bolts and coil springs. The Full-size cars used a different arm configuration (different ears), as well as being wider overall.

Camaros and Novas used leaf springs, and trucks used a completely different "12-bolt"

So A-body only... Some GTOs (455 powered) and maybe 442s used the "Chevy" 12-bolt...



I do recall that some of the early rearends (65?) might have slightly different "ear" heights, which require clearancing (and reinforcing) some arms, etc... This might have only been 1964 10-bolts (I can't recall)... But all "Chevelle" rear ends will bolt into other Chevelles...

No B-body (impala) 12-bolt ever had "ears". They had a 4-link (or 3-link depending on options, but I think all 12-bolts were 4-link) with upper bars mounted to brackets welded to the axle tubes.

If it's a 12-bolt, it has cast "ears", and it's a factory GM casting, then it's for an "A-body" (Chevelle, El Camino, Monte-Carlo).

The only "gotcha" that you have to watch for is something like a Moser or Strange casting for a 73+ Chevelle or 77+ Impala.

The only "gotcha" that you have to watch for is something like a Moser or Strange casting for a 73+ Chevelle or 77+ Impala.

I might add the shocks mount in front axle tubes, not the back like up to 1972s,

Interesting!!
Thanks for the info..

The only thing that I am concerned with is the actual casting portion of the rearend not the tubes or spring postions, etc for a coil spring chevy.

So it looks like if I specify an A-body 12-bolt then these rearends will:
1. Come with the cast-in ears.
2. The casting ears will be identical in height and lateral angle and bushing diameter to all other A-body rearends.

OK, so the A-body's are different from the B-body. Does anyone have a pic of a B-body housing for comparison?


Great Info and great help keep it coming!
Kevin

Interesting!!
Thanks for the info..

The only thing that I am concerned with is the actual casting portion of the rearend not the tubes or spring postions, etc for a coil spring chevy.

So it looks like if I specify an A-body 12-bolt then these rearends will:
1. Come with the cast-in ears.
2. The casting ears will be identical in height and lateral angle and bushing diameter to all other A-body rearends.

OK, so the A-body's are different from the B-body. Does anyone have a pic of a B-body housing for comparison?


Great Info and great help keep it coming!
Kevin

Some aftermarket housings have raised ears, helps traction (moves instant center). Same effect as no-hop bars. You might want to check with vender before ordering a new housing.

Yep, I know all about the aftermarket housings and I'm not ordering a new housing I just want to make sure I have the factory A-body 12-bolt info above correct.

Whatcha Think?
:)

Kevin Slaby

ps.. I'll send you a PM.

So it looks like if I specify an A-body 12-bolt then these rearends will:
1. Come with the cast-in ears.
2. The casting ears will be identical in height and lateral angle and bushing diameter to all other A-body rearends.Yes. :) (as long as it's a GM casting). '64s had smaller bushing diameter, but the 12-bolt didn't come out until '65.

OK, so the A-body's are different from the B-body. Does anyone have a pic of a B-body housing for comparison?B-body 12-bolts WILL NOT HAVE EARS. They have the same "pumpkin" castings as the Camaros and Novas.

The B-body didn't get "ears" on its axles until '77, but by then the 12-bolt had long since ceased production. Same with the 73-77 A-body... they only came with an 8.5" 10-bolt. No 12-bolts after '72.

Thanks Guys!
I think I got it!

Kevin Slaby

my friend had a 70 nova ss with a 12 bolt and it had ears, but also leaf spring perches, looked original to????? always thought that was wierd

my friend had a 70 nova ss with a 12 bolt and it had ears, but also leaf spring perches, looked original to????? always thought that was wierd
that just means that someone a long time ago welded leaf spring perches to an A body 12 bolt. after a few years of normal driving, the rust scale will make everything look "original" to the car if it the rear wasn't painted all pretty and kept clean.