んじゃあ、生きのいいうちに届けねえとなんねえな
Context: an employee which seems to deliver something for a store.
My take on the first half is: Well, (if I don't deliver/I have to deliver) it while I'm still full of vigor/energy...
What's with the なんねえな part? I can't get anything out of it apart from the な at the end.