Nbs 10.5 full floater rear axle swap??

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Jayss88

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I have got a 94 srw 3500 4x4 trying to swap the rear axle from a 03 2500hd with disc brakes. I know ill have to move spring perches and wms will end up 1.5-2” wider. Aside from that has anyone completed this and have any helpful insight or red flags? Ive searched relentlessly already and cant seem to find anyone that has done this successfully yet?
 

smdk2500

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I am thinking of doing the same. I have a line on the same axle your looking at. I just have to see if i can get the truck cheap enough. Its one of our work trucks and the trans is starting to die last time we sold a truck in the shape this one is in was dirt cheep. If i can get it ill have a 6.0 to play with too.

But back to your question the shock mounts are probably in the wrong place as well. Im not sure if the u joint is the the same between the two as well. Im not sure how the park brake cables hook up eaither. Might have to use a combination of parts from both trucks. The prop valve for the brakes might need swapped with one with rear disc brakes also. I dont know if it would be a problem if you ran the old one. Other then that i cant think of anything else that would cause any problems.
 

JayMB

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Shock mounts are different. NBS are angled and longer iirc while the OBS are straight and shorter. You'll have to move the spring perches out roughly 1" on either side. The U-joint on my 2006 AAM1050 from a 2500HD 6.0L has a 1410 U-joint yoke on the pinion. I think my 1999 14SF on my 1999 Suburban 2500 was a 1350 or something (smaller). You can use the adapter U-joint. I needed a new driveshaft because the larger ring gear pushes the pinion closer to the trans (need shorter driveshaft, by a little) and then mine is going up in the air too so it's different again. A 14FF to AAM1050 at stock height shouldn't have this problem but maybe check. Also the E-brake cables are a little different. Think I ended up using the e-brake cables and e-brake cable splitter bracket thing from a NBS to make it work. You might need a different prop valve for disc-disc. Good luck!
 

JayMB

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Also despite the bolt pattern being the same, the threads on the lugnuts are metric on the newer axle. M14x1.5 IIRC while your '94 should be 9/16" fine thread. You can just run different lugs on the rear wheels, it's no big deal. So long as you don't mix up which ones go where (or have someone at a tire shop do that). You could press out the studs and put SAE ones in your AAM1050 but they cost like $3.50 each, take forever and you need 16 of them. Maybe not worth it. Worth knowing though.
 

454cid

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Also despite the bolt pattern being the same, the threads on the lugnuts are metric on the newer axle. M14x1.5 IIRC while your '94 should be 9/16" fine thread. You can just run different lugs on the rear wheels, it's no big deal. So long as you don't mix up which ones go where (or have someone at a tire shop do that). You could press out the studs and put SAE ones in your AAM1050 but they cost like $3.50 each, take forever and you need 16 of them. Maybe not worth it. Worth knowing though.

The earlier GMT-400's are SAE? My 99 has metric lugs.... I just got done with rotors on the front, so I got to pound them out, and wire wheel them.
 

evilunclegrimace

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Also despite the bolt pattern being the same, the threads on the lugnuts are metric on the newer axle. M14x1.5 IIRC while your '94 should be 9/16" fine thread. You can just run different lugs on the rear wheels, it's no big deal. So long as you don't mix up which ones go where (or have someone at a tire shop do that). You could press out the studs and put SAE ones in your AAM1050 but they cost like $3.50 each, take forever and you need 16 of them. Maybe not worth it. Worth knowing though.


94 GMT 400's have metric threads.
 

JayMB

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Just wanted to confirm: I recalled wrongly. GMT400's are metric. We had one with a D60 up front that had SAE threads on the front lugs. I was wrong. Sorry for the misinformation.
 
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