This is an OEM Lincoln 240V Receptacle Cover. It is used on the following machine codes:

Commander 300, machine codes: 10443, 10469, 10470, 10642
Commander 500 (Deluxe), machine codes: 10600, 10705
Commander 500 (Standard), machine codes: 10599, 10704
SAE-400, machine code: 11808
Vantage 300 (Deutz), machine codes: 11185, 11528
Vantage 300 (Kubota) , machine codes: 11529, 11784, 11919, 12342, 12670
Vantage 400, machine codes: 11186, 11511
Vantage 400 (Kubota), machine codes: 11787, 11921
Vantage 400 (Perkins), machine codes: 11462, 11530, 11785, 11920, 12305, 12319
Vantage 500 (Deutz), machine codes: 10995, 11180, 11415, 11468, 11931, 11932, 11960
Vantage 500-I, machine codes: 11576, 11954, 11961, 12304