If one rear leaf spring is broken, Technician A suggests both should be replaced, while Technician B says to only replace the broken one. Who is correct?

In this scenario, the recommendation to replace both rear leaf springs when one is broken is the most appropriate course of action. Leaf springs work in pairs, and when one spring fails, it can lead to uneven weight distribution, handling issues, and increased wear on the remaining components of the suspension system. By replacing both springs, it's ensured that they will have the same characteristics, such as stiffness and ride height, which is crucial for maintaining balanced handling and stability.

In general practice, replacing both springs helps to maintain vehicle safety and performance, avoiding potential problems that can arise from having mismatched springs. This approach also typically leads to more consistent handling and can prevent future damage to other suspension components caused by uneven stresses. Ensuring that both springs are new is beneficial for achieving an optimal ride quality and prolonging the lifespan of the suspension system overall.