Unfortunately I've never seen or heard of a good way to identify the "type" of Citori stock. You can easily determine what type a receiver needs, but you can't really tell from the stock.
Sometimes based on a certain stock and checkering design, you can determine what model it came off of (325, 425, some of the trap models), but that's about it.
The forend is pretty easy based on the info @ Midwest Gun Works website, but the stock, not so much. The stock you show is the most generic stock Browning offered, and the same design was offered across all 3 types. Only way to know is try it on a receiver and see if it fits.
99% sure it will be a long tang stock as well.
While BucPride says Type 1, based on the picture, it looks identical to the stock the long tang Type 3 I started shooting with.