My shake is reallyl in the seat of my pants, between 30 and 40. As for 65, there is almost no chance for me to get it up to that speed in the suburban area I live in, unless I take it out in the middle of the night! It feels like driveline to me, but when I did get to see it up on the lift there is nothing obviously loose. The mechanic balanced the wheels, and commented that he thought there might be flat spots on the tires, but if so, they happened over night sitting in my driveway, because the first 3 weeks I drove the car it was quite smooth. Plus my mechanic was surly, with a bad attitude, and left me with zero confidence in the end. Hence this post. Plus in my reading, I find that the type of balancer used, right down to the make and model, is apparently important as well. I've been a mechanic by trade all my life, cars, boats, and now small engine, so I "get" it, but I'm less inclined to crawl around under jack stands than I once was, so finding someone who I can trust and will not talk down to me would be very welcome. Thank you for your response, I'm reading and learning more about Miata shakes and shimmies every day!