Speeding ticket has month and day no year - is it legal?

Yes, it most likely is legal -- it would depend on your state laws. Because it does not have a complete date, your lawyer might have grounds to contest the validity of the ticket, but that would just cost you lawyer fees. The only thing the prosecutor would need to do is to have the issuing officer testify to confirm the date of issue. If you got a speeding ticket, just pay the ticket or hire a lawyer to find all the loopholes for you.