I am in the process of restoring my 79 Tomos Bullet and recently bought side covers for it, they came as a set, but really only needed one. Anyway, my original side cover that is on the bike is plastic and the ones I bought are metal. I believe the ones I bought are off an early 80's model. Did Tomos change from plastic to metal at some point or is this a random thing? Just wondering, thanks! (good thing I got a set!)