Chevrolet Performance Heavy Duty Timing Chain.  This is a heavy duty single roller chain that uses an improved alloy steel and the side plates have an increased thickness to improve strength. If your are making cam change or a basic freshen-up on your engine, then you should consider replacing the timing chain.  This chain can be used on all LS engines and can be used with stock gears.

 NEW GM PART# 12646386 REPLACES OLD GM PART# 12586482