Mueller B & K 888-556 Stem Assembly Anti-Siphon Faucet Freezing, Pack of 1

Right brand, right length, but this does not look like the valve stem in my current faucet. Are the parts interchangeable?

Will this work in an American Valve M72AS Frost-Proof Antisiphon Sillcock? (I realize the length must be matched between 4" and 14" nominally)

It's to long. What size do you think I need.See my comment. The longest 8 inch stem (888-556) that I have seen. To long to replace my stem.

So, is this item 10 inches long or 13 inches long? The item is long and thin. It cannot be 10 inches by 13 inches by 1 inch!