The items under consideration are Center Bearing Support (CBS) Upper Bushing (Internal Part Number RG03140-B0/Customer Part Number NA15510000101) and Lower Bushing (Internal Part Number RG03141-B0/Customer Part Number NA15510000102), which are assembled onto a CBS and a vehicle undercarriage frame. The CBS bushings, in conjunction with the assembled CBS, reduce vibration through absorption of kinetic energy, which transfers to heat energy, thereby reducing the vibration from the propeller shaft to the undercarriage of a four-wheel drive vehicle. The CBS and CBS bushings are bracketed and bolted to a precise, engineered, bottom center location of the vehicle, which then absorbs vibrations from the propeller shaft and reduces vibration to the vehicle undercarriage frame. The CBS can function alone without the attachment of the CBS bushings, but its function would be inefficient and could cause damage to the vehicle. The bushings are composed of vulcanized synthetic rubber and carbon steel.
[1] Please importantly note that only the relevant portion of the related is displayed above. You may refer to the said customs ruling for the entire ruling explanation.
[1]. https://rulings.cbp.gov/ruling/N323406