I converted my 3500 to SRW about 4 years ago. I've included a note about the conversion in my signature on several forums. I get 1 or 2 PM's a week from people asking questions about doing an SRW swap. Back when the price of diesel was over $5.00 a gallon, I was getting 3 to 5 a week. So I thought I would post a write-up I did a few years ago. I don't mind answering PM's but it's easier just to reply with a link.
The conversion is actually very simple. As far as the front end goes, just remove the wheel spacers and install a set of rims from a 2500. You'll also need lug nuts. I bought a set of 32 lug nuts from Ebay that were used but in perfect shape for $20. The dealer wanted $8.00 for each one. I bought four used wheels off of a Ram 2500 from Craigslist for $200.
The rear end is just as easy. Pull off the dually wheels and install the 2500 wheels and lug nuts. The only other thing that I had to do was shorten the wheel lugs because they are too long to allow the wheel center cap to fit. You could change the lugs to 2500 lugs but I just cut them with a cut-off tool and then removed the lug nuts to clean-up the treads. It only took 10 minutes and the treads are perfect. The dually axle on the Dodge is about 4 inches wider than a 2500 axle. Most people assume it is narrower but it's actually wider because of the large offset of the dually wheels. I know 4 inches sounds like a lot but it's not noticeable. It's fine for stock width wheels and tires but if you are going to run wider tires you might want to consider a SRW axle. The only other difference from a stock SRW is the size of the brake hubs. It's not a functional problem but you do see more of the brake drum. The dually axle's rear brakes shoes are wider than the SRW axle. Combine the wider brake shoes with GM brake cylinders and the rear brakes become very strong.
The harder part of the conversion is the bed. You could take off the dually fenders and fix the bed but it would take a lot of body work. If you look at the attached photo you'll see several small holes that the bolts went through, a two inch hole for a marker light, a large hole for the fuel fill and a portion of metal removed above the wheel opening. I found it much easier to replace the bed. I got very lucky and found a bed and tailgate on Craigslist for $300.00. It had one very small dent and the paint was fading on the passenger's side but that wasn't a problem for me because I needed to paint it to match any way. There were just a few other things I had to do. I had to cut a few inches off of the rubber fuel fill hose which was done with a razor knife. I also had to swap the fuel fill inlet because of the large hole needed for a diesel fuel pump nozzle (the srw bed came from a gasser) but that was only 4 small screws. The last thing was to extend the rod that lowers the spare tire. It needed to be about one inch longer. Also, there is a grounding strap between the bed and frame that needs to be removed with one screw. Also worth noting, the dually tailgate and SRW tailgates are not identical. If I remember correctly, the SRW tailgate is wider at the bottom so you should get a SRW bed with a good tailgate.
I sold all the old parts. I actually made more than enough money to pay for my paint job and some body work. The dually fenders are a real money maker. Dodge wants a lot for them.
Truck as a dually. I also removed the tripod mirrors.