Scraper Evolution Series Exclusively from Diecast Masters: Continuing our special Evolution Series, Diecast Masters is proud to introduce highly detailed scale models of the Cat® No. 70 and 621K Wheel Tractor-Scraper. These newest releases join the Motor Grader, Track-Type, Wheel Loader, Track Loader and Off-Highway Trucks Evolution models previously introduced. Defining Scraper Technology from the 1940s Through Today: Diecast Masters pays homage to the rich history and remarkable sweep of earthmoving technology, beginning with some of the earliest machines and extending to the most recent. This story of Cat® scrapers is the sixth installment of the Evolution Series.