28 or 30 Spline Information

[candyredc10]

Hey everyone, I have a 1984 c10, and I'm in the market for a limited slip diff. Is there a way to tell if I have a 28 or 30 spline? I have a 250cu, 3-speed manual, and a 8.5 10-bolt. Any information helps.

 

[Itali83]

Pretty sure 30 spline 10 bolts didn’t come out until 88-89 ish. My 87 Jimmy has 28 spline. My 89 blazer has 30 spline. Both 350tbi motors 700r4 4x4 trucks.

Ben

 

[Curt]

All rear 10 bolts are 28spl for 84-85’.However,if you’re not the original owner,always verify something like that before ordering parts.If it has a open carrier now,chances are it is original.

 

[Poppy 87]

Welcome from Georgia!! Probably 28 spline

 

[PunH2O]

All rear 10 bolts are 28spl for 84-85’.However,if you’re not the original owner,always verify something like that before ordering parts.If it has a open carrier now,chances are it is original.

What about my 87 305 700r4 2wd 1/2 ton pickup?

 

[bucket]

What about my 87 305 700r4 2wd 1/2 ton pickup?

They were all 28 spline until sometime in the '88 model year. So as long as it's still the original axle, it will be a 28 spline carrier. If it's been replaced, then it's anyone's guess.

 

[Logbed]

Same dilemma. '85 C10 silverado 305+Th350. Looks tell its 10 bolt 8.5, speed+rpm+math tells the ratio is 3.42, but is there any way of telling the spline count from outside? I can't be sure if it is the original axle.

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