Generally speaking, it is legal to put seats in the bed of a pickup truck. According to the Federal Motor Vehicle Safety Standards, the bed of a pickup truck must be capable of accommodating up to three passengers, with each seat being no more than 20 inches from the floor. Additionally, all passengers must be securely seated in an approved seating system with restraining devices to prevent them from being thrown out of the vehicle in case of an accident.
Furthermore, different states have different laws regarding this matter. For example, some states such as California and Texas require that all passengers are seated in permanent seats that are bolted down and secured with seat belts or other restraining devices. Other states may require that the occupants wear seatbelts or other protective equipment while riding in the bed of a pickup truck.
It is also important to note that some states may not allow children to ride in the bed of a pickup truck at all, or they may impose restrictions on how many children can ride at once and how old they must be. Also, if you are transporting any type of hazardous materials or items such as firearms or explosives, you should check with your state’s laws regarding this issue before you transport them in your pickup truck’s bed.
In conclusion, it is generally legal to put seats in the bed of a pickup truck as long as it meets all applicable federal regulations and any additional state requirements that may apply. However, it is important to be aware of any additional state-specific regulations before transporting people or hazardous materials in your pickup truck’s bed.