Napa autoparts, a chain in california, had an aluminum
timing gear set that I used when I replaced the gear on
my 164. It didn't seem much heavier than the fiber set
that replaced it, and didn't make the car overly noisy.

When I first turned the car on, it made this wonderful
thrashing gear noise, but the oil squirters quickly quieted
the gears down to the point where I am not sure anyone
would guess that it's got metal gears.

The napa gear was about 1.5 times as expensive as the
fiber gear, and I assume that it will last for the life
of the motor.
chris