Rear end options

[Harleydave]

I currently have a '69 Firebird with LS2, T-56 McLeod RSX twin disc.
looking for some direction on rear end upgrades.
I currently have a stock 10 bolt with GM limited slip diff and 4.10 gear.
Discovered I have a slightly bent axle at the hub end.

My plan is to supercharge the engine and get to 600 rwhp range.
I could get by just swapping out the bent axle,but ultimately will need forged axles a stronger diff and a more suitable gear ratio.

Should I even bother with the 10 bolt,or just upgrade to a 9" now?
Budget is a bit of a concern as I will likely spend $6k on a LSA blower upgrade.

Anyone know of any deals on a lightly used built rear end?

[Pro Touring Store]

My opinion, do a 9".
If you don't go crazy, you can get one for like $2800-3800, all new.
If you're not tracking the car, a 10 bolt will suffice with that power.. But, C clipped rears aren't worth the money unless you find a deal on an already modified one or something.

-Dale

[dhutton]

Maybe an 8.5” 10 bolt? They are getting rare but still out there if you are patient.

Don

[Alwhite00]

Quick Performance 9" - best bang for the $$' 10k on mine with zero issues.

[Harleydave]

Maybe an 8.5” 10 bolt? They are getting rare but still out there if you are patient.

Don

I currently have an 8.5" corporate 10 bolt,GM limited slip diff,and 4.10 gear.
It has been painted with automotive quality gloss black paint and has a T/A performance billet cover with pinion brace.

Maybe I'll just upgrade/replace the bent axle and hunt for a used "built" 9 inch in the meantime??
I just missed out on a Currie 9 listed on here a month ago for $1000.

[Dave Pratt]

Harleydave I'm running an 8.5 10-bolt in my 69 Camaro. Also a GM limited slip.Upgraded to Moser axles,T/A Performance billet cover. 3.90 gears with 406 SBC making 450-460 at crank through a T-56.If you're putting big horsepower down the Ford 9 is the way to go. If you track the car definitely Ford 9 but some spirited street driving that 8.5 will take that all day long.Been running this setup for 7 years now without a blip...

[Harleydave]

Harleydave I'm running an 8.5 10-bolt in my 69 Camaro. Also a GM limited slip.Upgraded to Moser axles,T/A Performance billet cover. 3.90 gears with 406 SBC making 450-460 at crank through a T-56.If you're putting big horsepower down the Ford 9 is the way to go. If you track the car definitely Ford 9 but some spirited street driving that 8.5 will take that all day long.Been running this setup for 7 years now without a blip...

Thanks,I decided to just replace the bent axle and drive it for a while.
I'll probably upgrade to a 9" with a 3.50/3.73 gear when I upgrade to the supercharger.

[TheJDMan]

9" hands down. You can buy a Moser Engineering full floating axle rear end starting at $2876. I actually wish this package had been available when I was building Dust Off it would have saved me a lot of time and fabrication headaches.

https://www.moserengineering.com/9-F...d-Package.item

Depending on your T56 OD ratios you will want to rethink the rear end gear ratio. I'm running a T56 with .74 5th and .50 6th OD ratio, I have a 3.89 rear gear and it works great. I could also see where a 4.10 would work as well since I rarely get into 6th.

[Harleydave]

My LS2/T-56 is from an '05-06 GTO.
Looks like it's a 2.97 1st gear with a .057 6th gear.
Currently running a 25.7" rear tire with 4.10 rear gear.
1st gear is very short and almost useless at WOT.
I can only imagine what it would be like with an additional 150-200 hp.

[Lonnies Performance]

I've had good luck with Strange Engineering.
They make 12 bolts, 60's & 9" rears to suit your needs.

One nice thing you can do is ask for the Mopar style leaf spring brackets, instead of the U-shaped GM ones.
Pair this with a set of Caltracs & U-bolts & you have a good combination.

I cringed when & saw the 2.97 low... with a super charger, you may be better off with 3.42's or something similar.

I just removed my 4.10's when I supercharged my LS3 & I have a 2.66 low with 27.5" tires.
I needed 5th gear in the Quarter & traction was always an issue in 1st.

The 3.54's are way better. (lowest numerically you can get in a S60). Thats an equivalent of 2.92 gears with your tires/1st gear trans ratio for comparison.