How to verify if its a long or short pinion 10.25

jimcaf12

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My 1987 door tag shows I have a C5 axle supposed to be 410 Limited slip anyway I opened it up and its a 355 open diff,so im not sure if it was miss tagged or if the rear end was swaped,so Im doing a gear change and a Yukon posi ,I have it torn down wanting to order parts hoping there is a way to measure the pinion to verify weather its a short or long,,,thanks ahead for responses
 

austin92

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All modern production gears are 10.5 and long spline because it’s interchangeable. I have the yoke off a short spline pinion on my long spline 3.73 gears. Axle was a 10.25 out of a 94, new gears are 10.5 on a Detroit truetrac.


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jimcaf12

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All modern production gears are 10.5 and long spline because it’s interchangeable. I have the yoke off a short spline pinion on my long spline 3.73 gears. Axle was a 10.25 out of a 94, new gears are 10.5 on a Detroit truetrac.


austin92 what is the difference in the long and short because the part number for the gears end in a S for short and L for long,, is it just a deeper spline same length
 

Garbage_Mechan

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The VSS is not a for sure way to know, my 91 had a short pinion and vss. I’m really testing it out now, I swapped axles with my 96 so now the short pinion is behind the 460 hp 1000 ft lb Powerstroke!
 

Thewespaul

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The VSS is not a for sure way to know, my 91 had a short pinion and vss. I’m really testing it out now, I swapped axles with my 96 so now the short pinion is behind the 460 hp 1000 ft lb Powerstroke!
Now that’s an odd one, what was the speedo driven off of? Is it a 91 model or 91 build year?
 

Thewespaul

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Man that’s weird, I’ve got a 91 parts truck with vss and long pinion I’m putting eyes on here, learn something new every day.
 

snicklas

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Any IDI Era truck with RABS will have a VSS in the rear Differential, that's what rums the RABS.

87-91 the diff VSS is only for the RABS, it's a cable driven speedometer, and if it has an E4OD, there is another VSS "Dongle" that plugs into the speedo cable at the transmission/transfer case that's only for the TECA.

92 up (and for certain through the 6.0 trucks, probably even the brand new ones) the VSS in the diff runs the ABS and the speedo.
 

austin92

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The pinion gears are the same length. Splines are just longer for more strength.


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ifrythings

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If I remember right, I think the long pinion used straps to hold the u-joint as where the short pinion used u-bolts to secure the u-joint.
 

Garbage_Mechan

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I wish it were true but I just looked at my 91 short pinion spline and 96 long pinion spline and both have straps. Visually the short is 3/4 inch from the shortest point to the seal guard and the long is 1 1/2 so comparing the two you can see the length.
 

Philip1

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Looking online it looks like there is a measurable difference in the yoke length
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