I recently read a blog that you can determine the age/vintage of Stanley Planes by the number on the frog. I own a Stanley Bailey No. 4 smoother and I believe all the parts are original. The sole says Bailey No. 4 the frog has a "U" and a "6" on it. The cap iron has rhe registered tradmatk red color and Stanley. The opening is kidney shaped. So, what age might it be? I suspect after WW II but before the Handyman additions came out. What about it? Russell