I am installing a cummins diesel in an 85 dodge crewcab duelly. I have a dana 70 rear and need to know if it can handle a 550 hp cummins or should I go to a dana 80. I have 3.55 gears in a heavy duty dana 60 front out of the 92 intercooled 4x4 that is all being installed in the 85. I want to have disc brakes on the rear and I would like to have air suspension, with no springs on all four corners. Does any one make a conversion for that type of suspension for a first gen diesel 4x4? I could also use any advice available on the disc brake conversions.
Thank you for any information, or ideas, I can really use them right now as I am in the planning stage and not too far into this project to make changes. The frame has been modified to 4x4 from 4x2 and is ready for the suspension. The engine, transmission, and transfercase are ready to install, as soon as I have the rearend and suspension issues taken care of.

Snobuster

 

the 70 should be able to handel it, but an 80 wouldn't be a bad idea either and if you get one from an 01-02, it already has disk breaks, but there are alot of companies that sell disk conversion kits for the 70's and 80's, the air ride... i dont think there are any custom kits, but maby something universal, what year engine are you going with, and what do you plan to do to get 550hp?

here is what i did with my 75, all built from scratch, even the disk brake conversion

 

I am planning to have firerings in head and block, marine injectors, tweek thr injector pump and replace the turbo with a larger unit. I have a banks 5" exhaust and hi pro intake. I am thinking about the banks intercooler to go with it. I like the look of your air suspension, especially the long rails. I am not up to date on designing a system, but have been looking at the system on my diesel pusher motorhome, that bleeds down when you want it to ,to allow leveling or for easier access. The system you have looks very similar. Can you level the truck when loaded? My drive line is out of a 92 dodge heavy 4x4. I bought the entire vehicle as the frame was rusted thru and could not be driven. Engine and rest of driveline are in excellent condition. The truck I am building was a 1985 d300 crewcab dually long bed. I think it will be a great truck when I finish it.

 

my air system has a small 12v electrict compressor and a load valve over the rear axle, no matter how much weight i put on it or take off, it always stays at the same height it works great, the valve came from a semi,

and sorry to say, but 550hp, is all but impossible with the injection pump you have, it wil take quite a bit of work to get 300hp from it, but it will still be a beast, fire ringing the block isnt nessasary, and becomes very hard to deal with at times, and isnt needed untill you get up to 70-80 psi, i run just o-rings in the head on my 98, and studs only in my 75 (same as your engine), dont waist time or money with marine injectors, they arnt worth the hassel, the best i have found so far is DDP and some are liking the SDX, and you could also go with a p-pump conversion to get some awsome power

 

550 hp? I think you're going to want to get a beefier axle.

P-pump conversion is going to be required.

 

Thanks for the info, all of your input is a real help. I am just getting into this as this is my first diesel pickup, I have had a couple of big trucks with diesels but did not beef them up, just needed them to work hard. I wrote a long reply and it went somwhere I know not where so if it appears, consider the computer clutz has struck.

Thanks again for any and all ideas and thoughts.