The Peterbilt 357, 375, 377, and 379 1989 to 2007 Heavy Duty Washer Fluid Reservoir Cap is a black plastic cap that measures 57.9mm in diameter and 21mm tall, with a 53mm inside diameter and 21mm thickness. This snap-on cap is sold individually and serves as a direct replacement for cracked or lost original caps. It is application-specific, ensuring a seamless fit for certain vehicle years, makes, and models. With its excellent value, this cap offers a cost-effective alternative to dealership replacements. It fits most Peterbilt 357, 377, and 379 models from 1989 to 2007, as well as most Peterbilt 375 models from 1989 to 1999. Direct OE replacement number: Paccar 63361.