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thoughts on corporate rear diff

Aaron1505

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OK everyone I've got a 98 c3500 and the rear diff is past borrowed time. It has the removable drums while the axles are still bolted in and its a srw and its hard to find a rear diff that will just bolt in. So I bought a old rear out of a 73-87 that's in good shape and my plan is to cut the tubes off of my 98 rear and weld them back on to the older rear diff that is in good shape and basically make the same rear that came in my truck out of the two and use the axle shafts out of the 98. Is there any reason that this won't work? As far as I know the only thing that changed over the years was the widths someone please correct me if I am wrong about this. I'm just trying to keep my ole 6.5 on the road for the least cash I can
 

Aaron1505

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OK everyone I've got a 98 c3500 and the rear diff is past borrowed time. It has the removable drums while the axles are still bolted in and its a srw and its hard to find a rear diff that will just bolt in. So I bought a old rear out of a 73-87 that's in good shape and my plan is to cut the tubes off of my 98 rear and weld them back on to the older rear diff that is in good shape and basically make the same rear that came in my truck out of the two and use the axle shafts out of the 98. Is there any reason that this won't work? As far as I know the only thing that changed over the years was the widths someone please correct me if I am wrong about this. I'm just trying to keep my ole 6.5 on the road for the least cash I can
O and don't worry about my welding skills or the ability to get it straight I'm a boilermaker and I travel the country welding in powerplants for a living
 

WarWagon

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Why not just find a diff out of a 98 that fits? If you are going through that much trouble get a newer one and go 4 wheel disc brakes.
 

Aaron1505

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Because they are expensive around here and I picked up the rear for 250. Haven't seen a 14 bolt ff on cl or in the junk yards that would bolt in yet. How many trucks in 98 got a ff that were srw? Just want to know if my plan will work
 

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FRANKENBURBAN
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Because they are expensive around here and I picked up the rear for 250. Haven't seen a 14 bolt ff on cl or in the junk yards that would bolt in yet. How many trucks in 98 got a ff that were srw? Just want to know if my plan will work
Most 2500 pickups and burbs with a 454 or diesel got one, but not many 3500 srw trucks were built. I checked car-part.com and found a few in Indiana.
 

Aaron1505

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OK how much do they want? And will they bolt in or need perches rewelded? I've already got one I picked up for 250 that has no wear marks on the ring gear and looks to be low mile. The one I'm running now came in the truck and was run out of oil before I got it and wiped out the outside of the ring gear and took off a tooth or two off of the pinion and welded almost every thing together so I spent time with a file hone and a grinder and knocked off all the cracked teeth with a hammer and replaced all the berrings, didn't set the pre loamd or measure the pinion depth or check how they were meshing and that was over 30k ago. Don't think I even staked the pinion bnut and she's still going. its no big deal to cut and weld it up just want to see if it'll work
 

Will L.

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Carpatrt.com like mentioned above is always a quick check. Around here there a few junkyards that if you tell them what your after they call around in their network and get back to you in a few days.

It sounds like your still mobile at the moment. I would try to find the right one, or better yet do like WarWagon is saying, you'll really love the braking and the lower maintenance cost after that.

If you going to spend the time reworking something anyways, why not do the work toward an upgrade.
 

3500GMC

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Easy to swap parts into the OE housing. Maybe a few new bearings, some marking compound, time and patience- good to go.

Don't go hacking up axles and re-welding dude, you're just ASKING for trouble there.
 

Aaron1505

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The housing is shot so its not worth dumping any money into it and my plan is to cut and weld the axle tubes and then just swap the shafts. I've been looking on cl for a long time and people want more than I'm willing to spend for a newer one with factory discs. A 6010 open root with a 7018 cover pass should be more than sufficient to hold it together. Are the splined ends of the shafts the same?
 

Will L.

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The diff housing is cast steel iirc. 6010 is going to be to bar and will cause it to be brittle. The 7018 alone will do better. Or 11018 if you feel you need the overlap transfer from you root pass.
If my memory is off and it's cast iron then ni99 is best with ni55 as only other option.
Avoid the brittleness, there is a ton of vibrational forces there.

If you decide to go with your initial plan.
 

Aaron1505

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Not welding anything to the housing leaving some of the original tube and going off of that. I already have the diff so its the plan for this weekend.
 

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FRANKENBURBAN
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I think you're asking for trouble if you ever put true stress on it. The axle tubes are cast steel 1 piece from the factory, pressed into the cast iron center section, then spot welded in to keep them from turning. Correct axles ARE out there, so why hack one together when you can probably use one out of a 2500 truck that is a dime a dozen. Do some basic measurements and compre it to a 2500 axle and see how close it is before you go cutting and welding. And how do you know you're current housing is junk? Have you torn it down andd inspected it yet? If it was run dry, then chances are the outer axle bearings also got damaged, so welding on those ends is a waste of time in that situation. If your dead set on welding the tubes, then your going to need to make a jig to keep the tubes striaght when you but weld. Otherwise you will end up off center, and brake axle shafts.
 

NVW

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Welding an axle may get you in trouble if a DOT ever catches it.

A friend of mine had a spring hanger's welds break on a tandem truck, a welder rewelded it all around, the axle tube broke right off.
 

Will L.

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Welding an axle may get you in trouble if a DOT ever catches it.

A friend of mine had a spring hanger's welds break on a tandem truck, a welder rewelded it all around, the axle tube broke right off.
That's the heat range, wrong weld material, and or wrong welding technique.

Welding an axle tube to part of an axle tube? No. Do not do it. Dangerously bad idea. Run your current set up until it fails you on the side of the road if you have to waiting to find a different one.
 

NVW

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That's the heat range, wrong weld material, and or wrong welding technique.

Welding an axle tube to part of an axle tube? No. Do not do it. Dangerously bad idea. Run your current set up until it fails you on the side of the road if you have to waiting to find a different one.
It was more to do with a notch effect, the original hanger had 4 horizontal welds on the tube center. The new welds completely welded the hanger to the tube.
 

GM Guy

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www.car-part.com

Do some measuring, is there actually any difference in the axles between a 2500HD and a SRW 3500?

I am no expert, but did it actually ruin the housing, or can you change all the bearings and rebuild the current axle?
 

Aaron1505

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Ive already changed every bearing in the rear when I had it apart there's no bearing on the endof the pinion anymore because both the housing and pinion are shot. Can't remember what else is wrong with it at the moment.
 

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