Some specific pressure washers may require longer bolts and spacers to mount the pump to your engine. 5/16" 18 x 2 1/2" , One. 5/16" 18 x 3 1/2".It is the customers responsibility to make sure this is item will fit your unit. We usually respond within a few hours. We strive for 5-Star ratings and we will go out of our way to make you happy! We appreciate you taking the time to look at our product and will be honored to offer our services to you. The item "3100 PSI POWER PRESSURE WASHER PUMP Upgraded FITS EXVRB2321 VR2400" is in sale since Tuesday, September 30, 2014. This item is in the category "Home & Garden\Yard, Garden & Outdoor Living\Outdoor Power Equipment\Pressure Washers". The seller is "usapartsource" and is located in Lapeer, Michigan. This item can be shipped worldwide.