8.5 10 bolt 30 spline carrier to 28?

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Justin S

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Not exactly a GMT specific question, but its a fairly universal rear end figured I'd throw it out there. I have a Buick with an 8.5 10 bolt with 2.56 gears and i want to put in something like 4.10s. I already know to do this i need to swap the carrier due to the ratio change, and i know the GMTs come with the same 8.5s. My car has 28 spline axles and our trucks have 30. Im trying to do this on the cheap side, I don't want to spend $500+ on new parts. It would be pretty easy to find and snag a 4.10 carrier with ring and pinion from a truck in the junkyard, but is it just as easy as swapping over the spider gears between carriers so i can keep my 28 spline axles, or are they designed differently so that I can't do this?
 

JLG88

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I haven’t been able to find anything but 3.42’s and occasionally a 3.73 rear end at the yards by my house. Unless you step up to 3/4 ton but then it changes to a 14 bolt.
 

Knuckle Dragger

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Finding a possi carrier in the salvage yards will take a lot of luck, at least around here. A 8.5 open carrier for 4:11 should be a dime a dozen and the factory GM possi can usually be found on a lot of the forum sites for not much. I'm sure it's possible to swap the planetary gears but with the 8.5 28 spline being easier to find then the 30 splines stuff I think you're spinning your wheels (pun intended)

You could by 30 spline axles but you're looking at close to $300 for anything quality.

I don't think you'll find the 410s anywhere used.
 
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