Rear wheel drive the gear lube in the center also does the bearings. Front wheel drive the back wheels can either be greased as you would a front wheel bearing or they may be a sealed bearing that can't be greased.
The 2001 Mazda Tribute came equipped in a 2.0L L4 and 3.0L V6. The rear wheel bearing are sealed assemblies. These can be pressed in to complete the install. The OE replacement rear wheel bearings for this application are SKF #GRW266. It is recommended to replace the wheel bearings in pairs.
The rear wheel bearing, on a Nissan Maxima, can be removed by first removing the rear wheel. Next, remove the axle cover. Slide the wheel bearing off of the axle. Reverse the process to install the new wheel bearing.
Begin by removing the tire and wheel from your 1993 Nissan. Remove the end of the axle. Remove the wheel bearing nut. Remove the wheel seal and the wheel bearing. Reverse the process to install your new rear wheel bearing.