1970 GMC and Chevy trucks came with 30 spline Dana 60 I'm almost sure some of the 3/4 ton vans ,Ford, Mopar and GM came with them also, mayybe not You can change the side gears in the non 30 spline posi to 30 spline side gears

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)