SRW to DRW (Dana 70) conversion. Step by Step Instructions

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marmic26

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Hi All, I have a 97 k2500 HD. I always wanted a dually especially for towing. I search many forums and really couldn't find any information until I went to a Hot Rod shop one day, and the owner said just find a Chevy Dana 70 DRW axle and throw it in..... And that is what I did. Before I start, keep the hardware on the Corporate 14bolt rear as you will need to use the backing plate(s). My buddy and I picked up a Dana 70 Drw axle from the same shop that was on an 80's motor home. It also had the same gear ratio. 4:10. Previously I got the wrong axle that was on a C&C chassis. (Costly Mistake). Besides the axle I recommend new U bolts especially if you are in the Rust belt. 3500 rear shocks, and leaf springs. You will also need the DOT light, 3 red in the rear and the 5 amber ones the roof. I have found that the 2500hd and 3500 uses the same leaf spring although I think that information may be incorrect. So for now I have the existing leaf springs. Removing the 14bolt was a pain but I was able to drag it out. I was able to get some new spring perches, and shock mounts. I also had to get standard lug nuts, GM went metric in 87?. A year ago I was able to get the drw bed fenders, front spacers and 6 drw rims for $150. Please do use spacer to make it a DRW, the loaded weight will destroy the full floater axle bearing. Unless you going for looks. If you have access to a plasma cutter you can easily blow out the spring perches. I do not, and used the angle grinder. Depending on the axle you get, you might be able to use the existing spring perches and shock mounts. I place the 14 bolt and dana next to each other to for measurement. I did apply rust primer on the axle as well. My next post will be on hubs, seals, and brake hardware. I am waiting for AutoZone to give me new axle seals.
 

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packer0440

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I think dually leaf springs are heavier than 2500 HD and 3500 SRW, and they also include an overload spring with the brackets that contact them. Helps a lot.
 

Supercharged111

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This is the hard way to do it for sure. GM delivered duallies with 14 bolt rears and early ones got the Dana 70, so there are bolt in options out there. Marmic what exactly are you doing to the bed? There are sheet metal differences too.
 

RichLo

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I've been mulling over posting this reply but I feel that I have to from a safety point of view, especially since you plan to use the truck as any self respecting dually deserves to be used... hauling heavy loads.

I know you have put a lot of work into that axle since welding it but that is a very cold weld on the spring perch and should be ground down and re welded. The picture below is my weld that I did last summer on a 14b FF SRW for my snow plow truck. Granted, the weld is not the prettiest but that is a strong weld... concave weld pool, with even roots on the outside. Not a gummy worm laying on top of the two pieces of metal.

And a side note, that truck is built to be abused extremely heavily but not leave my driveway. I cut corners in places in places I wouldn't on street vehicles but not where strength and reliability matters.

Here is my thread detailing that axle swap. The beginning of this thread shows how important welds are on axles. The failure on the smaller GM 10 bolt axle was from the factory plug welds, which are still under hundreds of thousands of vehicles on the street today. Those factory plug welds were burned in way hotter than your spring perches.

Again, I am trying not to sound condescending but the weld you have currently WILL fail, its just a matter of when and how much damage happens as a result. Best case is it just flips your truck/trailer and you end up in the hospital for a month or two. Worst case you crash into a school bus and everybody dies.

Please take my response seriously and with a calm head. I really like this thread so far but I just cant morally see that weld and ignore it.
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