Will GMT 800 truck rear axle swap into GMT 400s?

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Chris Rogers

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I put GMT800 and GMT900 14FF in my square bodies all the time, just have to buy new spring pads and shock tabs.

how are you fixing the width issue. looking at doing a GMT900 under mine. need independent rear wheel speed and something other than the 10bolt that is in it (more power going in.). the mounts I understand. can these still be bought new from the dealer or is there an aftermarket version now?
 

EppNation

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Idk your width issue details, but in my case, putting a GMT800 axle on my GMT400 (burb in signature) damn near FIXES my width issue.

With the 8 lug Alcoa rims of the GMT800 era, I currently have a 2" offset between front and rear widths (front is wider).

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EppNation

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The width difference is completely normal.
Thought I read somewhere that it was these Alcoa rims that lead to or further increased this factory offset. Now that I'm thinking about it, does sound kinda silly.

None the less:
Normal ≠ Desirable
[in the instance of having differing front and rear axle widths]

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daturbosix

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anyone have the width measurement of a gmt800 1500 axle handy?
im considering swapping into my 2wd rcsb, i believe my 8.5 is 65-1/4"
 

EppNation

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Sry don't know much of anything about the 1/2 tons.

Can anyone tell me if there is a compatibility issue between a 14bolt with a 10.5" ring gear vs an 11.5"?

I've let more than one with the 11.5" slip though my hands because I'm not certain it will be as "plug and play".

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Triple

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Bumping this thread, looking for more info/photos regarding this swap.

You'd think it'd be a very popular upgrade, but I haven't found a single decent write-up.

Rather than swapping disc brakes onto my 99 K3500's current 14bolt, I would rather just replace the entire rear with an AAM 10.5 or 11.5. Better parts and performance all around.
 
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