If you narrow your 60's you are either going to need new custom inner shafts or cut and respline the stock ones but longs have been tested to be stronger than stock Dana 60 shafts. Especially the 30 spline stubs. But you will spend more on new Dana 60 shafts and 35 spline hubs than you would on longs and hub gears. And your truck would be much lighter with toy axles not to mention the clearance you would have over the d60's
