Dana 60 with upgraded slant six

Two words. Ford 8.8
Edit: more words.. way cheaper than either a Dana or 8 3/4. Can be found with good gears, disc's, and limited slip, for a quarter (or less) what an equivalent a-body 8 3/4 costs, plenty strong enough for a small block 408, and LOTS of performance upgrades available.
you tube for videos on how to narrow an explorer rear, with or without narrowing tools.