www.jdrace.com

The following carrier came with a 1969 GTO I bought years ago. I was told that it was a posi carrier for the car. I have seen pictures of original carriers online and they don't look like the carrier I have. Also the the carrier ring says 37 - 9, which would be gears for a 4.11, which was not offered in a GTO. The gearing for a ring gear of 37 teeth on a GTO would have had a pinion gear of 11 teeth for a 3.36 gear ration. From the pictures does anyone know what I have here?

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Last one

Where is the PINION?
It is a Buick Olds Pontiac Limited slip cone type posi original FACTORY unit.
The ring gear IS 4.11 set-up
I know it has GM stamped into the gear...BUT does not have a part number leading to me believing it is a OLD scholl after market gear like Zoom or some old performance gear brand...
If you do not have the pinion it is JUNK anyway so ditch the ring and use the posi

IF it did have 4.11 and was used hard you had better tear that unit down and see if the cones have bottomed out inside the case.
WE can rebuild and machine them once to get them back to good again but after that once is done it is a throw away unit from the factory.

4 spider gear unit was the best you could get back in the days SUPER DUTY pontiac Buick Olds unit. Started in 1967ish era all the way to 1972

what size ring gear bolt heads are on the unit?
IF - they are 3/4" you will have 7/16" x 2 left handed thread bolts and that would make the unit from a 1970 - 1972 era posi
IF - they are 11/16" headed bolt they will be right hand thread 3/8 x 24 and be from 1964-1969 era.
1969 could have either 7/16 or 3/8 bolts it was a transition year.

10 bolt 8.2 BOP unit. likely 4 series which holds 3.36 3.55 3.90 4.33 4.56 4.88 etc.

Jim
JD Race

Jim,

The bolts are 11/16" head. The carrier never came with the pinion and I never planned to use the ring gear. My hope was I would be able to use the ring and pinion (3.55) from my open carrier or worse case purchase a new set. Thanks for your help!

Blair

well it appears to have the correct offset to hold the 3.55 gear set make sure when you pull your open carrier you take both carriers and slide them side by side to make certain they ring gear lands are the same height. That will mean you can put the 3.55 on the carrier and offset will be correct.
You should be good as long as you double check your backlash. SWAPping a carrier is pretty straight forward.
Backlash is about all you will need to readjust -
Those are the shims outside your carrier races under the main bearing caps.