Well into the planning before I commit to cutting up my 2001 Dakota to be the donor chassis under my 56 pickup build. My Dak has a limited slip 9.25" 3:55 ratio on worn out leaf springs/hangers/bushings (the Dak has 203,000 miles on it). So I plan to fully rebuild the rear suspension/axle of my Dak before that all becomes the back half under the 56 frame. Wondering though, on the basis of building a better daily driver, would I be money and technology ahead, intead of rebuilding/repairing the 2001 Dakota rear axle, to get the entire rear end/suspension out of a salvage 1500 Ram? Thinking limited slip, same ratio, but then disc brakes and coil over suspension. A nicer package, no spring hangers, no axle tramp, better ride, option to include air load compensation inside the coil springs, a newer technology limited slip, better single ABS in the rear axle.

I feel I could easily spend over $500 just rebuilding/refurbing the original Dakota 9.25" rear axle, and have a decent rear axle/suspension that is still older tech and drum brakes. For that same money I could just get a much newer technology coil suspension rear axle with much better brakes and better rear axle ride/handling control.

What do you plan on doing about the width difference?

Aha, that's why I asked. Totally forgot about the potential for track width issues. Oh, and then there is the 4.5" 6-bolt hub pattern issue.

Hmm,...maybe use the suspension from a newer RAM 1500 and weld the mounts to the axle from my Dakota. That way I can maintain the right track width, and upgrade the suspension and brakes.

I think I would start with some measuring on the 56 bed width at the rear end location. The 56 was a full sized truck, back in the day. When I put my 49 on the Dakota chassis, I had to cut the bed sides to clear the tires on the mid 90s Dakota rear axle. The bed side cuts were below the bed floor, mainly because the bed floor is pretty high on these conversions.

The Ram 1500 rear axle width might work out better, but then you would need to deal with the wheel bolt pattern. I wonder what would be involved with swapping the Ram 1500 front brakes with the Dakota front brakes? Unless you are in love with the 6 bolt wheels, the 5 bolt Ram bolt pattern probably has more wheel options, if changing the front brakes over isn't a major issue. .

Just something more to think about.

Pic 1) The inside edge of the tire rubbed on the bed side, so I cut out the diameter of the tire for clearance. The holes in the bed side are the fender mounting holes, the 49 rear fenders were just large single wheel trailer fenders, the fender mounting holes on your 56 will be spaced farther apart and more of a 1/2 oval shape. The top 3 fender bolts are above the bed floor line, the other holes are all under the floor.
Pic 2) Just more of an angle. You can see the bed floor height in this pic, the floor is the black metal inside the bed side.

Yeah, I'll have to check that track width. My 2001 Dakota has a 61.5" rear axle track width. The RAM 1500 has a 64" to 71" track width. But after searching the subject a bit more I found a post by Gene regarding the rear axle track width on the Dakota chassis. Gene said "I think a 93 Dakota chassis will work well under a 55 Dodge 1/2 ton pickup. The width of the Dakota front and rear suspension (the rear suspension is good, but a Dakota rear axle is going to be 4" more narrow then your 55. You may have to put a mini tub in the box sides to clear a Dakota rear axle) is probably about the closest to the width of your 55 Dodge of any modern chassis."

Changing the front spindles to match the bolt pattern to the rear hubs may be an option to gain the better brakes and suspention from the RAM. But I don't thnk anything from a RAM front end will mount to the Dakota frame? Certainly someone here knows much more about swapping Mopar parts from a RAM onto a Dakota front end. I do know a 2003 Durango front spindles and brakes can mount right up to my 2001 Dakota chassis.

The 2006 and later Dakota uses the same 5 x 5.5 wheel bolt pattern as the RAM 1500 even way back in 2000.

Most of my parts interchange experience ended in 94 when I opened my welding shop. That was the point when most things I was under was older stuff needing welding, not much parts swapping like I was doing before that.

I know that with the introduction of the 97 Dakota trucks, the front wheel bearings went to the "sealed" bearing and hub assembly and would not interchange with the 96 and older trucks where the bearings and the rotors or hubs were separate parts. Both the later model Dakota and the Ram both had those "sealed" wheel bearing hubs and were sold as a unit with the hubs. It may be as easy as swapping the hubs, then adding the Ram brake rotors, or it may be way more complicated then that. Comparing the rotor sizes (the rotors have to match the caliper brackets on the frame, or the brackets also have to interchange) and checking to see if the bearings and housings themselves are interchangeable could go a long way to having the understanding you need. Back in the day, you could get those parts broke down into individual pieces and could actually source those individual parts, not so these days. Any interchange book (like the old Hollander's manual) would tell you the parts do not interchange simply because of the 5 or 6 lug pattern, they would not tell you the parts would actually bolt into place or not.

Thanks Gene. After doing some research I think the issue is more to select the best rear axle (2WD) with the best features and durability to handle close to 400 ft-lb of torque. I'd like disc rear brakes and rear axle ABS, but I could pass on both to get the best rear axle for the build.

Would be hard to find a better option then the 9 1/4 you already have in your Dakota. I think I would cut the bed sides for the tire clearance, and mini tub the bed if needed, then run wheels with less backspacing then the OEM Dakota wheels have.

As long as the pinion nut does not come loose, and the wheel bearings don't ruin the axles, the 9 1/4 rears were pretty tough. I believe they are capable of handling a lot more HP then you are looking at, and your truck will be mostly a street truck. Drag racing with big sticky slicks, front tire lifting traction, and more HP then you looking at, might change my mind.

Again, the voice of knowledge and reason, just the answer I need to understand what are my best options. There are options out there to improve the leaf spring suspension, and if I don't need to modify spring perches, and improve traction and reduce leaf spring distortion on heavy throttle/high traction. I'll be checking into rebuilding my 9-1/4 rear axle. Thank you Gene.

Would it be reasonable, if I found a complete salvage RAM coil over suspension cheap, like less than $500. Would it be reasonable to weld the RAM suspension mounts onto the rear axle from my 2001 Dakota (3.55 ratio, drum brakes, semi-posi) so it would fit under my 56 frame build.

Better get the RAM frame mount brackets as well. Hopefully you can adapt them onto your 56 frame and they will still line up with the Ram brackets welded to the Dakota rear end and you can use the Ram linkage.

Don't know how well just using the trailing arm mounting brackets off the Ram axle are going to work if you don't use the rest of the Ram trailing are set up. At least in theory, the Ram parts could be mounted with everything at the same time to assure alignment of the parts before permeant welding occurs. I would think a complete mounting system from an aftermarket supplier would work better then trying to adapt some of the Ram parts to a different aftermarket's designed parts will work out.
I have no experience with rear coil spring and trailing arm suspension, but mixing parts from one company to a different company doesn't sound like a good process.

Yup. Just throwing idea bait out on the line to see what gets a bite. A 4-bar link coilover panhard rod setup would be nice to control the rear axle, and help to eliminate axle wrap/hop especially on a light rear end truck with possibly 300+hp at the rear wheels. I know on my 56 build I will at minimum upgrade the leaf spring suspension to the best it can be. But a 4-bar coilover may be the better option, even when a complete new leak spring suspension runs close to $500.