The D number system is used by Caterpillar to denote the different crawler dozers they make. The wartime D4 weighed about 5 tons, the modern D4 tips the scales at about 9 tons. D7 wartime was about 12 tons, modern D7 is more than twice as heavy at 26 tons. I doubt that D7s could be air dropped. D4 was 62 in. wide, 122 in. long. D7, 98 in. wide, 162 in. long. Lengths are to end of drawbar.

Perry