Spools have a love hate relationship with most. I personally love them in the rear axle of my jeeps. I have a detroit in my 60 now and will likely put a spool in when I regear.
Pros: It's very predictable in on road driving, no parts to fail offroad, cheap, and doesn't break if you blow a shaft apart.
Cons: Wears tires faster on the street, increases turning radius (to same as a rear end while locked), and you can't turn it off.
Make sure if/when you order one you order for the correct 60, they aren't all 35 spline and most 60 spools are!