It is what is referred to as an Ithaca "NID" model, made from 1926 until the very late forties. Ithaca probably put a few together in the early fifties. NID translates to "New Ithaca Double". It is a strong, good quality gun and is worth repairing. The stock can probably be repaired. The replacement would be quite expensive if done by a proper stockmaker. Someone here will suggest a gunsmith with parts available.