I will post since I'm literally in the middle of swapping my 8 3/4 for a Dana right now. Looking like I will end up with around $1400 in the Dana. Wish I would have took the advice to do it first.
Started with a craigslist truck Dana for $150. Got it torn down cleaned up and painted. Just pulled the 8 3/4 this weekend out of the Dart so I can haul both housing to Moser. This way they can shorten it to match what I had, weld the perches at same place and angle, weld on Mopar ends, build me custom axles. I am lucky to kind of close to Moser so I can let them do the measuring
From there I am buying the power lock sure grip from Dr Diff along with needed bearings, seals, ect. When all put back together will slap it in and measure for my new driveshaft with 1350 u joints. Luckily my truck Dana came with perfect looking 3.54 gears so I'll be reusing them.
Can't wait to get this done and get it back to the track to see how bad the change from 3.91 to 3.54 will hurt me. Slapping on a Procharger this spring so that is the reason for the Dana and gear ratio.