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Pinion Spline for the early 8 3/4 489 case

Houle #382

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Just wondering if anyone knows what the pinion spline is on the 68 /69 8 3/4 489 case would be. I want to put 3:39's in but they list two different splines, a 10 spline and a 29 spline
 
Just wondering if anyone knows what the pinion spline is on the 68 /69 8 3/4 489 case would be. I want to put 3:39's in but they list two different splines, a 10 spline and a 29 spline
Depends on the yoke you currently have? You can run either just need the correct yoke
 
2.76, 2.93, 3.23, 3.31, 3.55, 3.73, 3.91, 4.10, 4.56, 4.89, 5.17, 5.57.
I don't see a 3.39
The race gears (no longer available?) had some different ratios
29 spline is stronger but you can break anything
Gears are harder to find for the Small center section
472 and 489 are easier
us gear makes a 4.86, 5.13
Check Richmond gear 5:38
you should be able to find a 3.23 or 3.31 all together- they were very popular
 
I've had two factory 3.23 gear sets for a '489 case. one was 10 spline the other 29 spline. I believe the 10 spline was an original gear for a '69 car.
 
There is a reason we went to 29 splines
the root of the shaft is larger
 
2.76, 2.93, 3.23, 3.31, 3.55, 3.73, 3.91, 4.10, 4.56, 4.89, 5.17, 5.57.
I don't see a 3.39
The race gears (no longer available?) had some different ratios
29 spline is stronger but you can break anything
Gears are harder to find for the Small center section
472 and 489 are easier
us gear makes a 4.86, 5.13
Check Richmond gear 5:38
you should be able to find a 3.23 or 3.31 all together- they were very popular

My bad 3:91's not 3:39's, need to proof read before entering ! Going to purchase Richmond Gears
 
I like the 75-140 fully synthetic gear oils
check for your posi compatibility
you may have to use an additive
 
Real question is what is the spline on your yoke
worst case is you have to buy a new U joint yoke
 
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