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Does anyone know how similar the 1500 van frame is to the 2500 & 3500 frames? Can I snag a 1500 frame section for test fitting the diff and have results transferrable to the 2500 & 3500 frames, or is there too much difference?
they are the same..crossmember will be different for the smaller/shorter 4l60e
 

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I found this on a Facebook advert:



This is a 1500 AWD van, but I need to check the parts lookup to see if I can find the crossmember, as that could either just be used or serve as a starting point for a crossmember that would work.

I see that the control arm pivot boxes hang down lower than the RWD ones do, so that would have to be dealt with in order to use this part... neither super east nor bolt-in. But nothing fun is bolt-in.

I also just noticed that the rear/lower diff mounts sit on this crossmember. I guess the forward/upper diff mounts bolt to brackets on the frame?
 

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they are the same..crossmember will be different for the smaller/shorter 4l60e
With the 1500 vans using a rack and pinion, is the front frame crossmember different? Could be an issue mocking on it vs the 2500-3500 frame.
 

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With the 1500 vans using a rack and pinion, is the front frame crossmember different? Could be an issue mocking on it vs the 2500-3500 frame.
Maybe the crossmember is the same and the rack will bolt up to the 2500/3500 frame?
We should be so lucky... but that would certainly help with diff clearance to the steering linkage.
 

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Maybe the crossmember is the same and the rack will bolt up to the 2500/3500 frame?
We should be so lucky... but that would certainly help with diff clearance to the steering linkage.
the half ton steering rack is not what you would want on a 1 ton van....theres a reason GM stuck with a steering gearbox on IFS trucks. The front crossmember is slightly different for the AWD steering rack, but just some added bosses for it...the under engine/differential crossmember for the AWD/7.5" front diff is way to small and shallow to work on a 9.25" diff with a duramax..
 

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They stuck with the recirculating ball worm/sector steering box because it's cheap, already in use and change is expensive.

If I bend the crossmember, I'll build a better one. I don't think that will be a problem.
The diff bushing locations are right next to the hard points bolted to the control arm pivot pockets. That means the bending moment in the middle of the crossmember from loading due to diff torque reaction is comparatively small.

The further apart I put the diff mounts in the fore/aft direction, the less load is on them per ftlb of axle torque.
 

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They stuck with the recirculating ball worm/sector steering box because it's cheap, already in use and change is expensive.
and stronger

If I bend the crossmember, I'll build a better one.
I doubt bending it would be an issue, it simply would be too shallow to fit around the larger differential, and even if it did fit it is all too high up and won't allow for the size and location of the duramax...Art had absolute fits trying to make a duramax fit into a quigley converted rolling chassis..
 

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That's really the packaging exercise that has to be done...
The rearward limit on the position of the diff is approach of the axle tube to the oil pan. The forward limit on the position of the diff is interference between the diff cover and steering linkage.
 

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That's really the packaging exercise that has to be done...
The rearward limit on the position of the diff is approach of the axle tube to the oil pan. The forward limit on the position of the diff is interference between the diff cover and steering linkage.
exactly...it's tight but not too bad with a 5.3LS and 7.5" diff...with the duramax and 9.25 you really only have the option of lowering the diff to create the needed space
 

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exactly...it's tight but not too bad with a 5.3LS and 7.5" diff...with the duramax and 9.25 you really only have the option of lowering the diff to create the needed space
Which is why the rack & pinion steering caught my eye...
 

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Which is why the rack & pinion steering caught my eye...
I'm new to posting here,but i have read this thread several times.
I have a 2019 3500 express that i am going to convert to 4wd.
It has the 6L90 trans and Timberline conversions sells an adapter kit to mate up to a tcase.
I'm using a NP242 tcase out of a hummer.
I'm doing this at my backyard shop and i will not be taking the body off the frame.
I don't have a lift,but i do have a service pit.
I'm going to use an 8 1/4 front diff, I'm easy on stuff,it should be fine.
No rock crawling for me.
 

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i will post pics,for sure.
We live in Port St Joe Fl,at PSJ we can drive on the beach so we wanted to have 4wd for that and we tow the van behind our motorhome,putting the transfer case into neutral will allow us to tow it with ease.
We have a Wanderlodge Motorhome,500hp so the van is not a problem to tow.
Info on Wanderlodges can be found at www.wanderlodgeownersgroup.com
The van will act as an enclosed trailer as well as a get around vehicle when we travel.
 

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I don't think anyone is posting about cutting metal right now...
I have a diff, torsion bar crossmember & torsion bars. I'll be snagging a 1500 AWD diff crossmember sometime soon. I'm working with a local yard to get a mock-up frame section, but this is not the only project I'm working on.

and stronger
Maybe? I have a hard time believing that an assembly that can take the forces of a hydraulic assist will be "weak", although the tie rods failing in buckling would be the potential weak point and highly unlikely to be encountered unless rock crawling. That likelihood can also be judged by looking at the diameter and length of the tie rod ends.
If you're going to take your van rock crawling, just install the 5" truck lift and bolt the 4WD system together without any cutting. A near stock-height van is not good for that kind of off-roading anyway due to wheel base and ground clearance.

I doubt bending it would be an issue, it simply would be too shallow to fit around the larger differential,
That's certainly a possibility... although I would rather have something to start from and modify than build from scratch.
 

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i want to tow mine behind my bus,to do so would require a Remco driveshaft disconnect or Tcase,
I towed Asro vans for years with the disconnect,and i just don't want to go that way,plus i live on the beach in Fl and want to be able to drive on the beach.
The AWD vans are not towable as built,so i'm building one that is.
 

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The Astro vans have a neutral in the T-Case, but the Express/Savana vans do not? Interesting
 
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