Modern neoprene type seals for your Buick engine! Installation of these modern seals is much easier than the old style rope type seals, ensuring a positive seal every time. All of our rear main seals are No Trim, Direct Fit, while other suppliers offer a more difficult to use Trim-to-Fit seal. The use of neoprene seals will also free horsepower because the drag on the crank is only a fraction of that compared to rope seals.