ORIGINAL: Jeff489
Where did you get them gear covers?
Those are black capped transmissions from Tamiya, standard on their full option tanks.
Your transmissions look like Type 1 transmissions (also from Tamiya), that are an older design. The black caps have brass gears down toward the final drive where the stress is greatest, and plastic gears up near the motor where the speeds are high (to keep it quiet). Type 1s are just as dependable as the black capped version (in my experience), but will make your tiger run way too fast. Most guys use a 3:1 gear down unit on them to slow them to scale speed, which works real good.
If curious, check out RSEA's thread on his tiger geardown saga. His Tiger has a set just like yours and he installed the geardowns.
Be careful with the early gear boxes. The brass output shaft on the end of the final drive is prone to slipping. It was eliminated on later TUs. Bob, thecommnadernj