Yes, a Grizzly 660 does have transmission fluid. The amount and type of transmission fluid may vary depending on the year and model of the ATV, so it's important to check your owner's manual to be sure. Transmission fluid helps to keep the gears in your ATV's transmission lubricated and cool, and ensures smooth shifting. If you notice any strange noises or shifting issues with your Grizzly 660, it could be a sign that the transmission fluid needs to be checked or changed.