All laborers and mechanics employed by contractors or subcontractors (excluding tribes and tribal organizations) in the construction, alteration, or repair, including painting or decorating of buildings or other facilities in connection with contracts or grants entered into pursuant to this chapter, shall be paid wages at not less than those prevailing on similar construction in the locality, as determined by the Secretary of Labor in accordance with sections 3141–3144, 3146, and 3147 of title 40. With respect to construction, alteration, or repair work to which the Act of March 3, 1921 1

Notwithstanding subsections (a) and (b) of this section, with respect to any self-determination contract, or portion of a self-determination contract, that is intended to benefit one tribe, the tribal employment or contract preference laws adopted by such tribe shall govern with respect to the administration of the contract or portion of the contract.