67 coronet 8 3/4 in A-body

I think the "A Body 8-3/4" I bought for my 66 was out of a Coronet. I wound up having it narrowed to fit under my Dart and buying custom axles. cost me three times what I planned to spend on a diff. I would put something else under it had I known the trouble. I hope it holds up after the $1800.00 spent on it!