Dana 60

I built the Dana 60 in my 66 Dart without a spreader and it turned out great. Preload was spot on and it works perfectly.

Lots of people do. But I am not going to recommend it when that's not the proper way to get the job done. You can get a case spreader for well under 100 bucks or possibly even borrow or rent one. Rear ends are not cheap and I am not going to recommend any way but the correct way. That's just how I do it. If you or others have had good luck otherwise, that's great.