Will an 8 3/4 rear end fit in a 73 dart sport?

Yeah that rear axle is just too wide for the car. They they rigged the front hangers and shackles. I wouldn't be havin any of it like that, but it's your car so you need to proceed how you want to. I would narrow that rear end to stock A body width like I did the 9" I am getting ready to put in my car......but of course then there's more expense involved. In the end, it would be more "correct".
Interesting. We are still thinking on it. Maybe we will end up narrowing it like you. What are you putting your 9 inch in? And if we were to narrow it, how would that interact with a new set of leaf springs? Any fabrication required for that?

Also really the only reason we aren’t too worried about the leaf spring location was because they ran the shackles along the section of the frames that go toward the back of the car. However, we would still need spacers between the dif and and leaf springs to account for the mounting location. The spacers they used were very uneven…