Just to clear that up a little more, poly and rubber bushing are for street cars, spherical bushings are for race cars. There are no dust shields or boots on the spherical bushings. If you have a race car, that doesn't matter, because it doesn't get driven enough. On a street car, all the road dust and dirt gets into the spherical bushing and wears it out quickly. The spherical bushings are also hard, for the race track, where ride quality isn't a factor. I have been doing this a long time, and have made many of the mistakes of putting race car parts on my street car.
Kurt