29 CFR § 500.103 - Activities not subject to vehicle safety standards.
(a) Agricultural machinery and equipment excluded. Vehicle safety standards or insurance requirements issued under the Act and these regulations do not apply to the transportation of any seasonal or migrant agricultural worker on a tractor, combine, harvester, picker, other similar machinery and equipment while such worker is actually engaged in the planting, cultivating, or harvesting of any agricultural commodity or the care of livestock or poultry. This exclusion applies only to workers carrying out these activities on such machinery and equipment or being engaged in transportation incidental thereto. The exclusion does not include the use of such machinery for the transportation of any worker under any other circumstances.
(b) Exclusion for immediate family transporting family members. The standards of this subpart do not apply to an individual migrant or seasonal agricultural worker when the only other occupants of that individual's vehicle consist of his immediate family members as defined in § 500.20(o).
(c) Carpooling. Vehicle safety standards or insurance requirements of the Act and these regulations do not apply to carpooling arrangements made by the workers themselves, using one of the workers' own vehicles and not specifically directed or requested by an agricultural employer or agricultural association. Carpooling, however, does not include any transportation arrangement in which a farm labor contractor participates.