you might want to try your local electrical distributr(s) I know her ei
Savannah there are three and they all either carry boxes or can order  them.
I am not sure where you are but if your city is large enough and you are
fortunate enought to have one check with the electronics distributers  They
may not have it but they can direct you to a manufacturer and you can then
get them of the internet if you are looking for a quantity

Eddie, Turner, kc4awz

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