i run a dana for a number of reasons. the dana may weigh slightly more, but has less rotating drag due to the fact that the pinion centerline is closer to the ring gear centerline (vertically). granted there is tons of aftermarket support for the 9", but i just didn't want a ford based rear in my car. that and i've broken a 9". and an 8 3/4. and an 8 1/4. i also agonized over which posi to use. i have a full spool. it was the right decision for me.