Brand new complete 4x4 Servo Assembly ready to Plug and Play and compatible with Yamaha ATV's Feel the pride of repairing your own equipment with an easy DIY install - No special tools required. We specialize in parts and repair services for the Yamaha 4wd system. You may find this part cheaper from another supplier, but I guarantee you won't find better service and the ability to talk to the owner of the company on the phone who will walk you through troubleshooting your 4wd system. This servo fits the following models. 2003-06 Big Bear 400 2004-06 Bruin 350 2007-2014 Grizzly 350 Solid Rear Axle 1998-01 Grizzly 600 2000-06 Kodiak 400 2020-Up Kodiak 450 w/o diff lock 2006-10 Wolverine 450 2004-19 Rhino and Grizzly Clones (Hysung,Big Muddy,Etc) 4wd servo function explained.... The servo assembly is the black plastic housing that is mounted on the front differential. It does the work of actually engaging the 2wd, 4wd and diff lock functions.