The only thing I've ever done to make them better (all I know) is obviously the shortest flange, to flange width you can work with helps keep it from bending the tubes forward, and putting a Mark Williams cap, or something like it on the left side carrier bearing since that's the one that wants out under load.
Herb McCandless built my last Dana for me and recommended the MW cap on the left carrier bearing as well, mostly because I intended on using a transbrake in the car. He said that the extra load from the brake turned that bearing from an "if" to a "when" it would break. He said the MW cap on the other side definitely wouldn't hurt, but it also wasn't overly necessary.
Other than that, good axles, a good spool, good Spicer bearings, and a good Pro gear is a recipe for longevity for what most people here are using their cars for.
