You'll see two versions of the trans kit generally available, identical except one has these rings, the other does not. The kit without is for people who are replacing the synchronizer assemblies, which include the rings. No one should attempt to recondition a transmission without replacing the rings, one way or the other. The rings are made bronze for a reason- they wear out first, to reduce wear on the synchronizers. Ford went too far on the M5R2, using nylon rings in the Thunderbird. My SC had already been converted to bronze when I got it, using F-150 rings.