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 from Proflow centre the front or rear cover when it is installed, and allow an easy way to install the seal by lightly tapping on the tool with rubber mallet. Choose from three styles of these alignment tools for front and rear covers. Plastic construction with O-rings.