i doubt you'll destroy that 3.08 unless you manage to get the tires to hook.
if the engine simply wont run at low RPM, and you need a low rear, you might go for a Ford 9", but unless you drop some serious jack in the suspension and tires, it will never hook anyway. if it does, you might want a roll cage, or at the very least, SF connectors.
If it doesn't hook, the majority of the wear is going to the tires anyway... but SF connectors wouldn't be a bad idea either way.
the 3.08/4spd could do fine in a street/highway application, esp if you get a cover which holds the carrier bearing caps in place.
