I tried to locate the tool for you but came up empty handed. The actual fastner is manufactured by a company in Kalamazoo, MI. Midwest Tools. The fastner's real name has changed over the years. Originally they were called corregated fastners and came in a variety of sizes and each package of fastners came with a free tool. They were made out of aluminum and were pretty well worn out after a bunch of uses. The tool matched the size of the fastners. Today those fastners are called "wood joiners" but they are the same thing. Unfortunately they don't come with a tool any longer. The fastners are difficult to get in straight without the tool. You might be better off using a different style fastner and some good glue. I no longer use those fastners because they tend to split wood. I prefer other kinds of joinery such as biscuits and pocket holes. They are much stronger methods of joining wood and much less likely to damage the peices.
By the way - you can buy the corregated fastners at any Oberchaun or Ace Hardware store. If you get lucky they might even have an old tool in their stock.