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Discussion Starter #1 (Edited)
When purchasing a new ring and pinion set, I noticed both 28-spline and 35-spline pinions are available for Ford 9" rear ends. Any way to tell what your car is equipped with without dropping the pumpkin, pulling the pinion and checking it out? I assume 28-spline is the norm/stock and 35-spline is like a racing application which wouldn't be on a stock vehicle?
 

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Only factory choices were 28 or 31 spline. 28 spline are much more common, 31 spline being limited to a handful of high-performance applications.

Pull a hubcap and look at the exposed end of the axle shaft. If you see a big dished oval its 28 spline. 3 small round holes means 31. Assuming they're the original parts.
 

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Discussion Starter #3
That's the axle spline count, not the pinion spline count, but thank you for the quick reply. As I understand it (which isnt saying much) the pinion spline count has nothing to do with the axle spline count.
 

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Sorry, read your original post to quickly. All factory Cougar applications were 28 spline pinions, to the best of my knowledge.
If you want to double check, you should be able to do it by simply dropping the driveshaft and looking at the splines behind the pinion nut. Shouldn't be necessary to pull the third member.
 

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I assume 28-spline is the norm/stock and 35-spline is like a racing application which wouldn't be on a stock vehicle?
Correct and you'll need more parts to make the 35 spline pinion to work. Don't worry though. The 28 spline will hold easily to 750HP.
 

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That's the axle spline count, not the pinion spline count, but thank you for the quick reply. As I understand it (which isnt saying much) the pinion spline count has nothing to do with the axle spline count.
Axle spline count has to match the pinion count or else fun things happen. Cj750 is right Factory was 28 or 31 on the performance big blocks and Eliminators
 

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'' Axle spline count has to match the pinion count or else fun things happen.'' NO IT DOESN"T Pinion spline has nothing to do with axle spline. you're thinking about the carrier pinions the axle slip into.
 

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Axle spline count has to match the pinion count or else fun things happen. Cj750 is right Factory was 28 or 31 on the performance big blocks and Eliminators
Sorry Copy Cat but that's wrong. PINION splines have nothing to do with AXLE splines.
The pinion splines mate to the yoke. You can have a 35 spline pinion and a 31 spline axle.
 

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Uh huh, Thinking more of center sections than gears, sorry!
 
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