Sergei said:Melissa its very easy - you just need some knife & file or grinder with cutting blade.
You just cutting out "frameP" of side of your new clock in existing housing, and then got to remove some plastic bits to make it fit snuggly.
Clock itself runs off 2 wires as you may see, and you got 3 in your existing plug. I cant remember which ones to use
Few drops of 3M glue for plastic may help too
Or you can just get a clock out of a '95 Classic.
I didn't know you could use and older Classic clock.