The LS engine uses front timing cover and rear main seal cover made from cast aluminum. Each has a seal pressed in to keep the oil on the crankshaft from leaking out. Between each cover and the engine block are seals made from stamped aluminum impregnated with a rubber seal. Aligning these covers is critical to ensure there are no leaks. There is a set of simple tools that make the alignment process very easy. Sac City Corvette sells a complete set of Alignit tools that will work on every LS engine. The three-piece kit includes a rear main, front timing cover and simulator tool.

These pictures show the simulator tool. This aligns the front cover with the seal installed.

This picture shows the complete kit. The two larger tools align the front and rear covers without the seals installed. This is the most accurate way of aligning the covers.

The Alignit tool kit is available here: http://www.saccitycorvette.com/AlignItTools.html