I'd get a timing gear and have it handy unless you are planning on going on
a long trip. They usually give pretty good warning before they let go-
sounds like a rod knock - and they can be noisy for quite a while before
they do let go. If properly lubricated the failure mode is usually that
the fiber gear disbonds from the knurled steel hub. When it is loose all the
way around the knocking starts and continues until the matching knurling is
beaten enough that the max torque causes it to slip. (It will frequently
stop at the right place once the load is less so you have a momentary loss
in power but by the time you get stopped it may be idling perfectly.)

On the other hand if you are taking your great grandmother on a long road
trip, maybe you better replace it now.
--
George Downs Bartlesville, Heart of the USA!