Rotating electrical parts are listed by OEM number and by output rating. Two alternators can share a bolt pattern and differ in amperage, which shows up as a slow battery drain rather than an obvious failure. Match the rating on the label of the original unit.
Batteries are listed by group size and terminal layout where the manufacturer specifies them. Confirm the group size against the vehicle tray before ordering: a battery that fits the terminals but not the hold-down will not pass inspection.
