You probably either stripped or bent the shift arm on both transmissions. I don't think your going to need a full rebuild, most likely just replacing broken or bent external parts or dropping the pan and replacing a broken or bent lever.
With the load put on the trans from parking on the steep hill could have stuck the trans in park and you damaged the shift arm or shaft forcing out of park.Should be an easy fix.
Did it take a good pull to shift out of park?
You should set the park brake before putting the trans in park on steep grade.