Synchronizer Rings

Do not interchange them. When reusing synchronizer rings, always install to the same gear.
Check for wear and replace if necessary.
Check the grooves -arrow 1- on the synchronizer ring -A- and the inner race for flat areas (grooves are worn).

Fig 1: Identifying Wear On Synchronizer Rings
Courtesy of VOLKSWAGEN UNITED STATES, INC.
The coating on the synchronizer rings must not be damaged.
If an intermediate ring -B- is installed, check the intermediate ring on the outer contact surface -arrow 2- and inner contact surface -arrow 3- for grooves, scoring and blue coloring (from overheating.
Check taper of drive gear for grooves and scoring.
Coat the synchronizer rings with transmission fluid and then install.