Shimmy at speed, non-lbc

[bstinocher@unipres.com]

List,

I have a car-related question, but not for my TR250 in particular. My Miata will
start to shimmy at around 63 mph, and stop at around 70 mph. In looking at the
manual, it says that if the shimmy persists at the same RPM, then it ISN'T the
driveshaft. Am I to assume that if it is only between these speeds, and not at a
certain RPM, that it most probably is the driveshaft?

Thanks.