The timing cover and rear cover on GM LS series engines don't have any dowel pins to ensure correct alignment to the centerline of the crankshaft & this often leads to annoying leaks at the front damper seal and rear main seal. These special alignment tools center the front or rear cover when it is installed, and allow an easy way to install the seal (by lightly tapping on the tool w/ rubber mallet). Choose from (3) styles of these alignment tools. Plastic construction w/O-rings. Made in the USA.