Save yourself a lot of hassle and go with the same brand & model. By doing so you'll avoid having to remount and mess with the drain & sink connections. Save the old power cord so you don't have to buy a new one. You'll need to do some very minimal wiring work to pull the wires from the terminals in the old disposal and attach them to the disposal. Make sure to attach the green grounding wire to avoid getting shocked when you switch on the disposal!
Typically, garbage disposals usually last anywhere from 5 to 10 years. Well manufactured units may even last longer than that. If you’re really looking to save some money, you can always disconnect your unit, dissect it, seal the crack and reattach it. However, this is just a temporary fix. If you have the money, it’s best just to invest in a new unit.
While inspecting your unit, if you see leaking, you will need to equip yourself with a screwdriver and tighten up the clamp that’s holding the garbage disposal to the dishwasher. The smaller drain line is attached by screws. Tighten up these screws and if the gasket is worn, replace this too (Careful not to overtighten). You should be able to purchase gaskets at your local home improvement store for a fairly inexpensive price.
If your garbage disposal is making a clicking or rattling sound, there may be some food particles that will not grind up inside. Remove power from disposer, reach into the sink hole with a pair of tongs and remove anything that is still down in the disposer. Test your disposer to be sure the noise is gone. If not continue troubleshooting your disposer issue (see below).