Never put in or changed the fluid(dealer always took care of that). Where is the plug located, how to check it and how to add the fluid?

 

5/16" drain plug and hex head fill plug on the left side of the diff. Items 21,22 on the parts break down. Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse Again this cheap 5 buck service manual can help on simple service,fluid requirements, quantities,etc along with repairs when needed.2006 Polaris Magnum 330 Service Manual PDF Download

 

Thanks, I plan on buying that service manual