Main bearing STD "Aluminiumalloy" By Brand KING .
Ford:
351C (1970-74).
351CJ (1970-74).
Short Tech Secs. From KING:
AM - this is the softest bi-metal material. It contains 20% of tin, 1% of copper and no silicon.
AM bearings are used in the passenger cars with low and medium load gasoline engines. Lead Free.
Commonly, the lining is made of an aluminum alloy containing 6-20% of tin.
More information you can get here.