HEATER CORE 1998 PETE B20011S / 3X010005

The heater core is a small radiator that uses hot engine coolant to warm the cab; a leaking or clogged core will cause poor heat output, fogged windows, or a sweet coolant smell inside the truck. This unit is listed as replacing both the PACCAR 3X010005 and B20011S OE numbers, which were used in different Peterbilt heater boxes, but the two originals have different dimensions and hose connections—so you must verify your truck’s specific heater core dimensions and fitting style before purchase. Typical construction is copper-brass for efficient heat transfer and durability in a heavy-truck environment.