I hate to be the bearer of bad news, but if you try to buy it from Abu, by the time you get all the components, it will cost as much as a new reel. I did that with a Revo MGX. Lost the side plate and well, now my Revo is used for parts for the others in case I need some. You can also try to buy a used STX, if you can find it for cheap and put on that side plate. Sorry I can't be of more help.
"Practice, practice and more practice, and if you think you're good practice some more". circa 2006, Cadman