Incomplete vehicles are partially manufactured by an Original Equipment Manufacturer (OEM) and subsequently sold to and completed by a final-stage manufacturer. Section S8.8, Final-Stage Manufacturers and Alterers, of Federal Motor Vehicle Safety Standard (FMVSS) 126 states “Vehicle that are manufactured in two or more stages or that are altered (within the meaning of 49 CFR 567.7) after having been previously certified in accordance with Part 567 of this chapter, are not subject to the requirements of S8.1 through S8.5. Instead, all vehicles produced by these manufacturers on or after September 1, 2012, must comply with this standard.” The FMVSS 126 compliance of the completed vehicle can be certified in three ways: by the OEM provided no alterations are made to identified components (TYPE 1), conditionally by the OEM provided the final-stage manufacturer follows specific guidelines (TYPE 2), or by the final-stage manufacturer (TYPE 3). An engineering solution to provide TYPE 2 certification boundaries for FMVSS 126 compliance to final-stage manufacturers of incomplete vehicles was found using a combination of physical tests and Hardware-in-the-Loop (HIL) simulations. The requirements to comply with FMVSS 135 (Hydraulic Brake Systems) and FVMSS301 (Fuel System Integrity MPV's, Trucks, and Buses) were used to limit the scope of the investigation. FMVSS 301 compliance restricts the maximum unloaded vehicle curb weight, providing a vehicle weight boundary condition other than the maximum gross vehicle weight. FMVSS 135 provides longitudinal and vertical restrictions on center of gravity location for the completed vehicle. HIL tests were performed to guide targeted physical tests. The HIL results were then correlated to the physical tests. The correlated model was then used to determine pass/fail center of gravity locations for each of the incomplete vehicle model configurations. TYPE 2 FMVSS 126 compliance was achieved by restricting the lateral, longitudinal, and vertical location of the completed vehicle's center of gravity.