G-Body Built Rear End Options

[1998gpgt]

I have a 455/TH350 powered 85 Cutlass that has been a bit on the slower side since buying it last summer. I started digging into a little deeper after taking it out of storage this year. It turns out I have a 2.13 gear in the stock 7.5" 10 bolt rear end.

I am looking to go with a 3.70/3.73 gear and am currently weighing my options. The main two directions that seem to be plausible are:

1.) Throw a 3.73 ring and pinion in the factory 7.5" 10 Bolt.

2.) Bolt in a Ford 9" 3.70 drum-to-drum assembly.

It is primarily a street car that may see the track once or twice a year. At this point in time, I have no plans of running anything other than street tires. I am not ruling out rocking a sticky tire at some point in the future though. I do not wish to put any money into the stock rear end if its destruction is inevitable behind the power/torque of a 455. I would rather spend a bit more and do it right the first time.

Any suggestions on which route to take?

Who should I go through for a 9" Ford assembly?

Click to read more...

 

[LikeABauce302]

It a depends on your budget. You can have a 9" built for $2500+ or you can find a 12 bolt and build it for less.

Since you probably won't run at the track very often, a 12 bolt with some upgrades to strengthen it will work just fine.

 

[1998gpgt]

It a depends on your budget. You can have a 9" built for $2500+ or you can find a 12 bolt and build it for less.

Since you probably won't run at the track very often, a 12 bolt with some upgrades to strengthen it will work just fine.

Rearend Swap Tech This article makes it seem like the Ford 9" is the most painless solution. https://www.quickperformance.com/mobile/9-Ford-Complete-Rearend-GM-G-Body-78-87_p_20384.html. This seems like a pretty decent price for a bolt in solution.

What kind of price would I be looking at to build a 12 bolt?

 

[b4black]

Why not get 8.5" rear from a Grand National or Hurst/Olds? The H/O rear would be a 3.73.


Or get a posi 7.5" rear from a Monte SS for cheap. That would also be a 3.73 and if you're sticking with street tires, it will handle it.

 

[LikeABauce302]

Wow, that 9" is a really good deal. If they are reputable, that looks like a good option.

If you want a local shop, I had a 9" built by VRN welding in Lake Bluff and have nothing but good thinges to say. Mine was more of an all out drag setup, but I'm sure he could build something less extreme than what I went with.