If you're buying Duralast (AutoZone brand) parts thats your problem, I haven't had a single Duralast part not let me down yet, cheap Taiwanese garbage, go to NAPA, Ford, or bronco graveyard (they have parts for pickups too) if you want parts that wont die immediately. Also some stuff from Advance Auto is okay, depends on where it's made. O'Mally's I cant speak for since there's not one in my area.
When I changed starters in my bronco I got the high torque starter from bronco graveyard, works great, will even start the truck in gear with no problem (not generally a good idea though).