Some questions

I was wondering about the composition of the components of the bottom end of the motor. Forged or cast, aluminum or steel. How many mains? Also I was wondering if the ignition coils are interchangable. Thanks.

Stephen

GM won't pay to forge anything! All aluminum block, cast iron crank and rods, chilled iron cylinder liners. The four main bearing saddles are cast into the lower block half. The coils are numbered for convenience only.