(a) Equipment included. Roll-over protective structures (ROPS) and seat belts shall be installed on—
(1) Crawler tractors and crawler loaders;
(3) Wheel loaders and wheel tractors;
(4) The tractor portion of semi-mounted scrapers, dumpers, water wagons, bottom-dump wagons, rear-dump wagons, and towed fifth wheel attachments;
(5) Skid-steer loaders; and
(6) Agricultural tractors.