Steve,
Good to know. I'm a huge believer in preventative repair... but, in order to be effective without throwing huge amounts of money at it, past history of the design is badly needed...
My data point is only one car... that's now 7 years old with about 95K on the clock... so, I'll put a pair of spheres on my list for when the weather warms up...
Many thanks.

__________________
KenP

1996 S500 W140 Coupe