1971 Olds Cutlass Supreme
350 Rocket V8
TH 350 Transmission

I was wondering how I could find out what kind of rearend I have got under there?

 

If the rear has never been changed,then it is an 8.5" 10-bolt.As far as ratio goes,the typical Cutlass Supreme came with a 2:56,2:73,or 3:08 ratio,unless it was ordered with something numerically higher,like a 3:23 or 3:42.

 

Shoot some pics will ID it here on the board for you. Take care, Jim

JD

 

Everytime I try and pull up Limited Slip Differentials on summit for the 1971 olds cutlass it always shows me the 8.2 not the 8.5. What the?

I have a 10 bolt 8.5 with 28 spline axles.

This is the one I prefer.

Moser Engineering 542050 - Moser Engineering Auburn Pro Series Limited Slip Differentials

Gear, Ring and Pinion, 3.42:1 Ratio, GM, 8.5/8.625

 

What are you going to do with the car. IF you zare NOT drag racing full time DO NOT do the AUBURN PRO. You will junk it in a year. They put too much spring preload on that posi unit and it eats itself FAST. Do the HP auburn or Eaton Or true trac.

PM me I can cut you a MUCH better deal than Summit racing WHICH will not KNOW the rear you are dealing with.

Jim
JD

 

Jim, what's your price on a Detroit Locker and Motive 3.90 gears for an 8.5" Corporate? I'm also looking for Moser axles as well...

 

Moser Engineering 542018 - Moser Engineering Auburn High Performance

Is one better for the street?

$395

 

You must be looking at a old catalog...lol try 430.00 for that unit know. They raised all there prices 6%

I have this unit for 350.00 No box deal. Jim


The difference is the preload spring pressure and angle of the cone engagement. IT is very aggressive for drag racing and terrible street manners which like i said earlier will eat itself quick and leave you with out posi action.


JD

 

OUCH, DETROIT LOCKER? do you really need and or want one of those?

How fast are you going and how often are you racing? How much street to race are you doing?

3.90 gears are 155.00
rebuild kit 85.00
LOOKS LIKE 640.00 IS THE BEST I AM GOING TO GET ON THE DETROIT UNIT

WE DO MUCH BETTER ON TRUE TRAC AND eATON TYPE POSI UNITS.

JD

 

The detroit locker is the closest thing you will get to a spool.I like them,but you can also have great success with a tuned clutch style unit,like an Eaton.
If you are going to upgrade to aftermarket axles,AND change the unit,now is the time to upgrade to 30-spline.The cost of the axles are the same,and the cost of the units are the same.

 

I am just trying to see where you are at with the car...? I see in your signature 350 CI motor...So a posi would be just fine and the same stocker 28 spline axle would be ok too. If your planning on a 500+ HP motor and racing the bajesus outof it then i would consider the axles and detroit.

IF you just want to have it I can not deny that request. Jim

355.00 for the axles with studs and access hole drilled.

28 or 30 spline.

I HAVE 30 SPLINE ON THE SHELF RIGHT NOW

J D