Tow bars came in a number of kits back in the 60's, however I don't recall all of them. My guess is in the AMT '32 Ford Roadster, and the Buick Special Wagon with trailer. There have been others also, and maybe some other modelers can name them.
I had to order my "Missle" from my LHS and paid a steep price for it, however I do believe in supporting my LHS and would sorely miss them if they "folded up." I only open 'bout 30 % of my kits, however I did open the Missle today to see if there was any body damage due to packaging. I even manange to get all the parts back in the box minus the body. The was everything was "crammed" in the box, one would think that this was a 3 in 1 kit. While I remember seeing these Super Stocks race back-in-the-day, I have no idea when I'll get to building my Missle kit as I have a lot of other models I'd like to get built also.