1978 mercury 20 hp wiring a aftermarket key switch

[Westvirginiahills]

I have a 1978 mercury 200 20 hp motor wires are black,salmon,gray,yellow,white,red and brown. Key switch letters are m,s,c,a,m and b.I have the manual but all the wires and letters do not match up need to know were wires go on aftermarket switch thanks for any help.