You want a full float not a semi float.
The full-float will have a big hub sticking out the center and 8-lugs. The semi-float will not have a hub sticking through the wheel and usually (perhaps always) is only 6-lug.
The semi-float is common in 1/2-ton and light duty 3/4-ton trucks. The full-float is usually under heavy duty 3/4-ton trucks and 1-tons that don't have a Dana.
Make sure you can tell a Dana from a 14-bolt though a Dana 70-HD the right width wouldn't be a bad thing.
