I have worked for Delta Air Lines for over 12 years. I have worked in Reservations, as a ticketing agent at...
I don't know what the restrictions are off the top of my head. I would contact reservations and ask them what the restrictions are. If the flight is very open there is a *chance* they wouldn't challenge you in bringing it on. (Let me stress that is a thin chance) But most likely with that size they would. If it is still in the original packing you could probably check it in. I would just check with Reservations to see what options you have.