Does anyone know why the limited slip units are listed 3.08 and up? I have a rear end that checks out at 3.08, but the tube stamp indicates 2.73 - unfortunately this is the break point for the posi units. Anyone know why? Thanks.

The 12 bolt and 8.2 10 bolt use a 2 series differential for the 2.73 gears and a 3 series differential for the 3.08-3.73 gears. The 12 bolt has a 4 series differential for gears from 4.10 through 6.00, but the 10 bolt uses the 3 series for these ratios. The difference is in the location of the ring gear flange. When the ratio goes up the pinion gets smaller and the ring gear has to move closer to the pinion center line. Ford just makes the ring gear thicker, but GM moves the flange over.

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'69 RS/SS396 Pro Street
427 4 speed 9"
Byars Performance
High Performance Drivetrain Parts & Service
www.lubedealer.com/biggearhead (http://www.lubedealer.com/biggearhead)

The tube stamp on the axle is GC C 118 2

The GC code is the 2.73 indicator, right? Are there any units available for this rear end or should I just plan on starting over. I was hoping to land in the 3.42 - 3.55 range.

You can always install a 3series gear on a 2series carrier just by using a spacer which is made for this purpose and is readily available from a gazillion sources. Keep this in mind, the big boys who do serious drag racing don't like to use a spacer because of a possibility that the longer bolts which are required may shear. But, if this is going to be a street/performance car, I wouldn't hesitate to use a spacer in a heartbeat. I have put together a few rears over the years using a spacer and have never had a single problem.

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Tom Parsons

Thanks for the tip Tom. This is a street car. Once again, the Chevelle group is a great place to be. I just need to locate a 2 to 3 series carrier spacer. I have not done any rear end work (yet), so I will go hunting.

I take it the spacer is for the ring gear to the hub? Looks like I will need some good bolts!

I don't recommend the spacer for strip or street. There is an area next to the ring gear flange that centers the ring gear on the differential case. When a spacer is used it moves the gear away from this area and can allow the ring gear to run off center. Using the proper differential is the best way to go. In some cases there are thicker ring gears available for using the 2 series differential, but not for the 12 bolt or 8.2 10 bolt. You still haven't mentioned which rear end you have. It does make a difference because some used the 3 series for the 2.73 gears and others used the 2 series for the 2.73. Eaton makes some very good positive traction differentials in the 3 and 4 series for all of the Chevy rear ends. They run around $348.

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'69 RS/SS396 Pro Street
427 4 speed 9"
Byars Performance
High Performance Drivetrain Parts & Service
www.lubedealer.com/biggearhead (http://www.lubedealer.com/biggearhead)

The cover indicates the rear end is an 8.2 10 bolt. The tube stamping would indicate a 2.73 non-posi I believe. I am just trying to amass information on this setup before I tear it down. Am I correct in assuming that I can bolt in a series 3 posi unit and a 3.73 ring and pinion and they will fit the rear end housing, right? I already have a posi unit that is designed for 3.08 and up, so it is a series 3. If I purchase an 8.2" 10 bolt ring and pinion it should all fit the housing. I checked Richmond Gear, they make a 3.73 for the 3 series 8.2 10 bolt.

Live and learn through Chevelles.com! This site is the best. Please let me know if I have this right/wrong. Thanks everyone! - Joe

Yes, if you have a 8.2 3 series posi you can put it in your housing with 3.73 gears. The 3.08 did come on the 3 series in the 8.2.

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'69 RS/SS396 Pro Street
427 4 speed 9"
Byars Performance
High Performance Drivetrain Parts & Service
www.lubedealer.com/biggearhead (http://www.lubedealer.com/biggearhead)