General Motors Specifications

GM 4342 – M

Code	Minimum Thickness (inches)	Plate/Chromate	Hours to Red Rust
50U48 30U40 20U32 15U24 10U8	0.0005 0.0003 0.0002 0.00015 0.0001	Zinc	48 40 32 24 8
50D96 30D96 20D96 50D72 30D72 20D72 30D48 20D48 20D24 10D24	0.0005 0.0003 0.0002 0.0005 0.0003 0.0002 0.0003 0.0002 0.0002 0.0001	Zinc & Chromate	96 96 96 72 72 72 48 48 24 24
50K48 20K32 20K24 20K8	0.0005 0.0002 0.0002 0.0002	Zinc & Clear Chromate	48 32 24 8
20L24 20L8	0.0002 0.0002	Black Zinc	24 8
20Z24 20Z8	0.0002 0.0002	Zinc & Chromate	24 8

GM 4252 – M

Code	Minimum Thickness (inches)	Plate	Hours to Red Rust
100 50 30 20 10	0.001 0.0005 0.0003 0.0002 0.0001	Nickel Over All Base Metals	32 NNS 16 NNS