Diecast metal.
The Caterpillar D6 track-type tractor is a medium bulldozer manufactured by Caterpillar Inc. with a nominal operating weight of 18 tons. The military versions were classified as the SNL G152 medium tractor, under the G-numbers classification system used for army tractors.
The D6 started out in 1935 as the RD6, fitted with a 3-cylinder 45 hp D6600 engine. The numbering was changed to the D6 in 1937. Caterpillar first introduced the entirely new D6 in 1941 with the 4R & 5R series. This was powered by the D4600 engine of 55 hp (drawbar).
The D6H was introduced in 1986 along with 3 other H-Series track-type tractors. This was the first D6 with Caterpillar's elevated drive sprocket undercarriage.