Which head gasket?

[SHOTZY]

Trying to figure out which gaskets to order. I have the factory gm manual and it says theres a, b, and c and that there are certain holes that will identify this. The figure points these out but doesnt match the dialogue. Or maybe its me. Can someone school me here please?

 

[LBZ]

You need to measure piston protrusion, and then using the GM spec for a minimum clearance between the piston and the head, pick the gasket that falls into that range.