. . . "Caterpillar DW6" . "Caterpillar D6B" . "Caterpillar D6H." . . "Caterpillar D6H" . . "D6T" . . . . "D6" . "Bsch 23T SP" . . "Bsch 18T" . . "Caterpillar D6" . . "D6 tractor" . . . . "Model D-6" . . . "Caterpillar RD6" . . "Caterpillar Inc. model D8" . . . . "Caterpillar AD63" . "Caterpillar D6" .