The Dana is going to be stronger given the critical fact "Detroit locker". Per Dr Diff on another thread some might remember:

"The size of the 9" differential is dictated by the presence of the third "pocket" bearing. Because of this, 9" differential internal parts are much smaller and weaker than the Dana 60 version. This is not a concern with a spool, but it gives the Dana 60 a big advantage for a heavy/torquey street/strip car with a traction differential."