According to the latest Kuhnhausen shop manual, they only sell those to factory approved armorers and sometimes not even then.
That book is highly recommended BTW even if you never open up a Smith.
Some "interesting" opinions are expressed.
It is indispensable if you do open up S&W's.
If I really wanted to get my model 69 barrel off I would get a length of square stock that fit down the barrel, plug the forcing cone with a small wooden plug, stick in the square stock and pour the barrel full of low temp Indalloy fixturing solder. You can get it that melts below 220f. When I was done I would put barrel or assembled gun in boiling water and clean with brass brush. You can save and reuse the solder.