I recently acquired a gray market 311 excavator. When I get a machine I like to change all fluids and filters to make sure that I know the fluids are fresh and have a baseline. I've got all the cat numbers for every filter except the air filter as the number has worn off and there was no secondary filter installed. The parts person did not seem very helpful and I want to make sure I get the right filter. Does anyone have a parts/service manual available and can look and advise the part number for the air filter?