REALISTIC cassette to 8-track tape adapter

Here's a fun gadget from the 1970's or so. (?) Still in its original box and packing with instructions sheet, this is a REALISTIC (Radio Shack) brand adapter to allow "cassette tapes" to be played by "8-track tape" players. Back when cassettes were overtaking 8-tracks in popularity but many vehicles were still equipped with the 8-track decks, these things were intended as a cheaper alternative to having one's car radio replaced entirely so the newer tape cassettes could also be played. It features controls for STOP, PLAY, and FAST FWD -- the latter being a function 8-track decks seldom were equipped to do.

I don't know if this particular unit still works or not (being mostly unable to test it for lack of an operable 8-track machine) but I'd imagine it does -- there really isn't much to them to go wrong, and since this one has apparently been carefully stored somewhere for a good while...??