Compliments of NHTSA
http://nhtsa.gov/cars/rules/im...55977
9. Importing a vehicle for parts.
If a vehicle originally manufactured for on-road use is shipped with its engine and drive train, it would be regarded as a motor vehicle for the purpose of the vehicle importation laws, and would have to be declared as such. If the vehicle was not originally manufactured to comply with all applicable FMVSS, it could not be lawfully imported unless it is determined eligible for importation by NHTSA and is imported by an RI or by a person who has a contract with an RI to modify the vehicle so that it conforms to all applicable standards following importation.
If a vehicle is shipped without its engine and drive train, it would be treated, for importation purposes, not as a motor vehicle but instead as an assemblage of motor vehicle equipment items. In this instance, the vehicle would be entered under Box 1 on the HS-7 Declaration form, which covers motor vehicle equipment not covered by a standard, or manufactured before the date that an applicable standard takes effect. Any items included in the assemblage that are subject to an FMVSS (brake hoses, brake fluid, glazing, lighting equipment, seat belt assemblies, tires, rims) that were not manufactured to comply with the applicable standard, and/or were not so certified by their original manufacturer, must be removed from the assemblage and exported or destroyed before entry. Any covered equipment items that were manufactured in compliance with the applicable FMVSS, and were so certified, must be entered under Box 2A.
10. Importing a disassembled vehicle.
A disassembled vehicle that is shipped without an engine and transmission is treated for importation purposes not as a motor vehicle, but instead as an assemblage of motor vehicle equipment items. Such an assemblage can lawfully be imported into the U.S., provided any equipment included in the assemblage that is subject to FMVSS, but was not originally manufactured to comply with that FMVSS or was not so certified by its original manufacturer, is removed from the assemblage prior to entry into the U.S. Equipment items that are subject to the FMVSS include tires, rims, brake hoses, brake fluid, seat belt assemblies, glazing materials, and lamps, reflective devices, and associated equipment.
If the assemblage is shipped with an engine and power train (even if those components are not installed), it would be regarded for importation purposes as a motor vehicle, and would have to be either manufactured to comply with all applicable FMVSS, and be so certified by its original manufacturer, in the form of a label permanently affixed to the vehicle, or be determined eligible for importation by NHTSA and be imported by an RI or by a person who has a contract with an RI to bring the vehicle into compliance with all applicable FMVSS after importation.