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

Dana67Dart said
Let's get a bit more info before you start replacing parts.

Do you have the rear end off the ground?

Is the engine and trans and driveshaft turning the rear, or are you spinning a wheel by hand?

What you are describing sounds like 1 of 2 things.

1. The brake drums are out of round and are dragging at the low point
2. The pinion angle is really off and the angle is causing the rear axle to speedup and slow down as the drive shaft rotates

We had it tested a couple months ago and nothing stood out to us. We had the back on jacks, and manually spun the wheels. Slight play in wheel but we were focused on getting running. Hopefully next weekend I will be able to do more testing and should find the problem. I should have been more clear. The main idea of this thread was to hear opinions on weather or not I should replace the rearend, while I’m back there. Thanks