i finally broke the 10 bolt in my Camaro this weekend. i'm thinking about going with a 12 bolt now. i know you can buy them for like 2500 bucks but i'm poor and unemployed so that is not an option. i know where i could probably get one but i don't know what to do about the torque arm. does anyone make a bracket for that? i thought i saw on the classifieds here once where someone had one for sale, it looked like it bolted to the back of the rearend under the cover maybe and went around and bolted to the torque arm, i don't remember for sure. i think it was made by summers brothers. if not, would it be best to try to make something like that or try to weld a bracket to the front of the housing? or would it be better/easier to use ladderbars or something like that? i'm also unsure of what gears to use. it has a carb'd 357 with a turbo 350. with the 2.73's it was running mid 13's i usually drive it to the track but i was considering the idea of getting a truck and trailer over the winter. would 3.73's be too much gear to drive on the highway at ~70 mph ish with no overdrive? just trying to get some ideas right now because i have all winter to fix it and i'll prolly have to get a job first anyways.

 

moser i think will sell the torque arm bracket, one of the makers of the thirdgen 12 bolt will if it's not moser. you could also make one and weld it to your housing. good chance the tubes wouldn't be the correct length but you could shorten, or lenghten them as you need. there are several people the sell fixtures for that, or you could make one, it wouldn't be hard to do and save you some jack. all in all if you were to buy some of the parts and tools for only one the 2500 might start to look like a bargin.

 

The adaptor bracket is only for the 9". The 9" has a steel housing that is easy to weld the bracket mounts onto. A 12 bolt has a cast housing that isn't recommended to be welded to.

Finding a 12 bolt is easy. Finding a 12 bolt car, not truck, diff that's the correct width isn't as easy. The car and truck 12 bolts are not the same. Trying to adapt a factory 12 bolt to fit under a third gen usually means changing the rear suspension to eliminate the torque arm.

As mentioned above, $2500 starts to become a deal when you realise what's involved in trying to adapt a diff not designed for the car.

 

how difficult is it to modify the tube length?
lets say you had to shorten it?

3.73 w/o overdrive would be a nightmare to drive. 3500RPM or so, and the motor would just be HOWLING. My 3.23 and no OD is just barely ok, my brother (with his 2.73 gear crown victoria) thinks it's awful. I just turn up the music.

I think you can buy the 9" housing with brackets for like $900, then just add you own "center section" and gears. I think a posi and gears should be cheaper than $1500, but that's just my guess.

 

you're also forgetting brakes that the $2500 setup includes as well. so $900+1k for center section and then the rest is brakes

 

you could mod your factory brakes to work.
Yeah, the truck and car 12-bolts are completely different, and welding to cast is very tricky at best, and VERY hard to do well enough to have any strength. I've looked at building a "bridge" structure from axle tube to axle tube, then a set of tabs that would bolt to this "bridge" and to the cover bolts. This would also require a custom tq arm. - There are a few ways to do it, but unless you're very handy with designing and building components like this, as previously stated, that $2500 can start looking pretty cheap.

The aftermarket 12-bolts designed for our cars have the tq arm mount cast in the housing, meaning the entire housing is cast specific to fit our cars. Just bolting to the cover bolts wouldn't provide enough strength to keep the axle from twisting.
As for switching suspension, there are many threads on the pros and cons to other types suspension. - ladder bars are basically drag race only, they don't do street to well at all.