What is this????

[Craig 85]

My best friend had a '71 C10 and had the same type 12 bolt with a 5 lug set up. I'm guessing someone changed the spring perches.

Here's a link to another forum discussing the 12 bolt.

http://67-72chevytrucks.com/vboard/showthread.php?t=486309

 

[SeanV]

Ok, here’s a shot of the rear chunk as well as the driver side spring and shock mount

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Those welds don’t look factory to me.

 

[SeanV]

My best friend had a '71 C10 and had the same type 12 bolt with a 5 lug set up. I'm guessing someone changed the spring perches.

Here's a link to another forum discussing the 12 bolt.

http://67-72chevytrucks.com/vboard/showthread.php?t=486309

And from a previous discussion with me trying to figure out how my 8 lug C20 Suburban ended up with 6 lug front disk brakes, we determined that for some reason, the previous owner installed CPP spindles on it to adapt the 71 6 lugs rotors on it. I theorized that rear 14 bolt was either robbed from the truck or it failed. In its place went this “whatever” 12 bolt with 6 lug axles. To keep the wheels all 6 lug, the guy installed the spindles and 6 lug rotors. And so....Bam! Here I am with this unidentified rear housing.

 

[bucket]

Agreed, those welds are not factory. The shock mounts do appear to be from another truck axle, but the spring perches are not factory looking at all. They are either fabricated from square tube or maybe purchased from a trailer parts shop.

 

[SeanV]

So chances are, we’re looking at 12 bolt truck unit from the 70-72 era with a welder-up conversion to work on the rear of a leaf spring truck?
So I guess my next question is: that rear is strong enough to do what I want, do I just add-a-leaf to bring my ride height and load capacity back up to “pretty close?” Or do I, or can I, order the correct replacement leaf springs for a C20?

 

[bucket]

Basically, consider it as a 1/2 ton and make a judgment call from there. Many people do way more with a 1/2 ton than others would even consider.

Just adding some rear air bags as helpers would probably be a good and simple option.

 

[SeanV]

Basically, consider it as a 1/2 ton and make a judgment call from there. Many people do way more with a 1/2 ton than others would even consider.

Just adding some rear air bags as helpers would probably be a good and simple option.

Ok thanks, that's what I'll do. To be honest, I'm kinda glad I have the 12 bolt with the higher gear ratio. These trucks were supposed to come with 4:11's or 4:56's. I have a 3:42 rear end in this one. Takes a bit of punch out of the 454, but makes a little, stress "little," better mileage on the highway.

 

[78C10BigTen]

Ok thanks, that's what I'll do. To be honest, I'm kinda glad I have the 12 bolt with the higher gear ratio. These trucks were supposed to come with 4:11's or 4:56's. I have a 3:42 rear end in this one. Takes a bit of punch out of the 454, but makes a little, stress "little," better mileage on the highway.

My c10 came with a 3.08 12 bolt and i put in a 3.42 10 bolt posi. With a th350 i honestly never saw much difference.

 

[bucket]

Ok thanks, that's what I'll do. To be honest, I'm kinda glad I have the 12 bolt with the higher gear ratio. These trucks were supposed to come with 4:11's or 4:56's. I have a 3:42 rear end in this one. Takes a bit of punch out of the 454, but makes a little, stress "little," better mileage on the highway.

I know what you are dealing with. Most of the year, my DD is my '78 C20 454 Suburban with 3.73's. It ain't bad mpg really, but it's not great either.

 

[Raider L]

It looks like a pan hard bar attachment point for some kind of vehicle. That looks like where it would be attached. And it only needs to be on the drivers side. I'll bet I'm right. It's a factory pan hard bar. It probably went to some K truck, or maybe a delivery vehicle?

 

[Raider L]

That big hole is for a bushing and the bar either attaches to a link or directly to that hole with a bushing in it.
A big rubber one.