As stated, the 8 inner bolts on the hub have to come out. This will allow you to pull the axleshaft out. When you do that, you will see a large nut (socket available for free rental at Autozone if you don't have one). It's been a while, but I believe there is a keyway and a lockring (it's been a while so others might be able to correct me if I'm wrong) as well.
This is what makes the axle a full floater (FF), the hub/drum is held on by the axle housing, not the axleshaft.
1/2 ton axles and 3/4 tons equipped with 14SF (if that was available) in 86 would have the "slip on" style drums, but not 3/4 and 1 tons equipped with a 14FF.