It's not a custom stock, it came from Springfield Armory with that bedded stock, from the factory in a factory box. It had a special model number or name on the box. I clearly remember these details except for the specific model number/name.
Serial # search has it made in '98. It's unfired but no box or papers. The previous owner bought it new, I was there. I'm inclined to think it is a NM model because of the bedding and thickness of the stock. My memory tells me that it had a specific model number but I can't remember what it was.