For CAT 279C, 279C2, 289C, 289C2, 299C. 1 Drive Sprocket. For CAT 279D, 279D3, 279DLRC, 289D, 289D3, 289DLRC, 299D, 299D2, 299D2XHP, 299D3, 299D3XE, 299D3XHP, 299DR, 299DRXE, 299DXHP. Communication is the best way to solve the problem.