I had the vacuum motors rebuilt on my '37 years ago, 15 at least, and they still work really good. I run a 250 inch engine that provides plenty of vacuum. Mine actually run too fast at full vacuum. Even at that, they do little to clean the windshield due to the little down force the springs provide. I use a lot of wax on the glass to help when cleaning bugs off, so water really isn't a problem anyway. In the 20 years I have own the truck, I've been caught in the rain twice and heavy fog once.
