A transverse spring rear crossmember is a structural component on a vehicle’s chassis that supports a transverse leaf spring (a spring mounted sideways across the vehicle) and the rear axle assembly. This type of suspension was common on early Ford models like the Model A and provides a clean, traditional hot rod look. The crossmember often incorporates a mounting plate for the spring and upper shock mounts, and is available as a replacement part or a custom upgrade for various chassis.