I'm going to get a new Haynes manual tomorrow, but does anyone know how difficult it is for a home DIYer to change rear wheel bearings on a B150?

 

well, i haven't done it yet, but was planning to on a buddy's 2nd gen, but then he sold it.

according to haynes, on a 2nd gen with corp 9.25, its easy... put rear end on jack stands and remove wheels. remove rear diff cover and drain oil. remove lock bolt and pinon shaft, then the c-clips. slide axles out. pry out seal from the center of the brake hub. use a slide hammer to grab/remove bearings from the axle housing. install new bearings, then seals, then axles, c clips, pinion shaft, lock bolt (w/locktite), cover (rtv as gasket), new oil.