OBS versus the 1999 Super Duty

The 7.3L ran in two distinct trucks. The 1995-1998 trucks are the OBS body with a different bracket and charging setup from the 1999 and later Super Duty. They take different alternators. If your truck is a 1999 or later, see our 1999-2007 Power Stroke page instead.

Why these trucks need the capacity

Glow plugs pull hard on cold starts and these trucks run dual batteries from the factory to handle it. Factory alternator output was modest even when new, and on a truck approaching thirty years old it is unlikely to be meeting its original rating.

Add a plow, winch, inverter or auxiliary lighting and the shortfall shows up immediately at idle.

Dual batteries

Replace both at once and match them. A new battery paired with a tired one is pulled down to the weaker one's condition, which wastes the new battery.

Don't skip the wiring

On a truck this age the factory cable is both undersized for a high output alternator and likely corroded at the terminations. Upgrading the three main runs is usually the highest-value change on the whole build. See our Big 3 wiring upgrade guide.

Browse all Mechman high output alternators or shop by vehicle.