Technical Chevy rear end folks, can you help me out?

I’m in the process of clearing space to do a disc brake swap for my ‘57 Chevy PU. It will be 4.75 BP.
I understand the 2nd Gen F Body rears are a good fit.
So I’m going to be on the hunt for a ‘70-‘7? 12 bolt rear.
Can someone remind me of the gear vs series of carrier needed?

Thanks.

 

the carriers you can buy list 3.08 to 3.90 for 3 series, and 4.10 up for 4 series.

 

Roadkill says Second Gen Camaro rears are 62.5 which sounds a tad wide from what you read from some sources but the bed is 50 inches on the inside and a frog hair more on the outside giving you 6-1/4 total inches of space between the bedside and the wheel mount surface for back spacing and tire clearance. Much more than a 255 tire doesn't fit in the space with decent clearance in and out and even then backspacing is critical.

 

Yep, more digging beyond “it’s a good fit”, show similar to being wider.

 

Might be best then to go with an 8.8 and get new axles made.

 

Second gen F bodies are 55.25" from flange to flange. 1st gen Camaros axles were actually wider, so I have installed a lot of 2nd gen ***es under 69 Camaros, poor mans narrowed rear end and an extra inch for wheels/tires once you kick the shocks inboard of the frame.
Watch the series 2 carriers in GM 12 bolts. No one wants a gear ratios with a 2 in front. They are common once the fuel embargos of the early 70's had us looking for gas mileage instead of fun.
And just because it has 12 bolts in the cover doesn't mean squat if you look at BOP rear ends.

 

I have always put 2nd gen Camaro rear ends in my 55-59 trucks . My daily driver has one with 8.5 " americans with 255 70 15s

 

I'm sorry Billy that is not correct. 1st gen rear end's ARE NOT wider than 2nd gen rear end's

 

OP also asked about the year of manufacture when he stated 70-7?. 12 bolt rearends were last installed in Camaros 1970 (one year only), in 1972 for Novas and Chevelles.

 

I put a 1970 El Camino 12 bolt in my 1936 Chev PU. It fit nice.

 

The 8.5 " ten bolt is a stout rear end compared to the earlier 8.25 10 bolt.

 

Geez, I haven't even been drinking but I have been taking oxy since surgery last week. Maybe it's time I backed off on those. I switched the whole thing around. The 2nd gens are wider by an inch than the seconds. ****, that was embarr***ing.

 

Don't need to.

The flanges on the axle shafts of an 8.8 have no extra holes in them, and are machined flat on both sides.

They can be re-drilled by any competent machinist, or with a drill jig.

 

Mike, you've answered your own problem here!
A V6 Exploder rear end is 3.7:1 posi with 31 spline axles, and disc brake rear end

You'll need a disc brake front conversion to match the disc brake rear-end
Grab the rear driveshaft flange and use a Precision Universal 447 U-Joint to adapt it to the Chevy driveshaft.

Also grab all the park brake cables for the rear end

You can make a drilling jig from an old rotor / disc [ preferably with a small centre hole that you machine for a tight fit ]

 

Thanks all. At first the focus was a 4.75 BP, but the 8.8 would be easier to get.
I think the truck might get to nasty with a 3.7x rear, 3.2x is better suited for it.

 

Auto Fox Bodies and V6 SN-95 Mustangs have 3.27 Ratios in their 8.8's but the axles are only 28 spline [4 stud]
go and vulture a C & P from your local U-pull

 

One more time

 

Thank you. Saved to pictures.

 

I agree on the 8.8 being the easier to find in junkyard and cheap. You better buy lottery tickets if you find a 2nd gen Camaro 12-bolt, those are fairly rare. Most 2nd gen have the 8.5 10-bolt which is a pretty strong rearend, although I think the 8.8 is even better choice for strength and junkyard availability.

 

Yes, found that out last night searching around. 12 bolts are hard to come by.

 

If you think a generic 12 bolt is hard to find, try and find one out of a 65/66Nova, when you do find one they cost about the same money as what the cars cost new.