Two technicians are discussing U-joints. Technician A says that a defective U-joint could cause a loud clunk when the transmission is shifted between Drive and Reverse. Technician B says a worn U-joint can cause a clicking sound when driving the vehicle in reverse. Which technician is correct?

Both technicians provide accurate information about U-joints and their effects on vehicle performance. A defective U-joint can indeed cause a loud clunk when shifting between Drive and Reverse. This occurs due to excessive play or misalignment in the joint, leading to sudden shifts in power transmission that create a pronounced noise.

On the other hand, a worn U-joint may produce a clicking sound when the vehicle is in reverse. This clicking can result from worn bearings within the U-joint, which cause irregular movement as the driveshaft rotates and engages the transmission.

In summary, both the loud clunk from a defective U-joint and the clicking sound from a worn U-joint are symptoms that can occur under different driving conditions, making the assertions of both technicians valid.