S.D. Codified Laws § 32-5-81
On receipt of any application under §§ 32-5-2 and 32-5-3, the county treasurer shall register the vehicle. Upon payment of the fee prescribed by law for the registration of the vehicle described in the application, the county treasurer or department shall issue a distinctive number plate. The registration for the vehicle shall identify the motor vehicle and the type of fuel used by the vehicle.
The applicant shall indicate the fuel type used in the motor vehicle as one of the following: gas only, diesel, liquified petroleum gas, or other. The treasurer shall reject any application that does not specify the type of fuel used. Any applicant who fails to correctly identify the fuel used in the applicant's motor vehicle is guilty of a Class 2 misdemeanor.
SDCL 32-5-81