If you have a 3/4" Banjo bolt on your brake line then the following part number should be what you are looking for. Polaris OEM number 2050078. A 1999 300 xplorer has the plastic type and not aluminum. Unfortunately the mastercylinder reservoir is not sold seperatly, it's only sold as the entire assembly. From us this part will run you $130.00 plus shipping. If interested give us a call PJ'S CYCLE 1-866-230-9923 or you can reach us by email at firstname.lastname@example.org
. We sell OEM and Aftermarket parts below retail pricing. Visa, Mastercard, & Discover Accepted. Hope this helps & good luck.