With the muffler removed, look through the exhaust port at the piston. If it is a one piece unit, from bottom to top, it is an ABC (or ABN; same technique), If there is a ring there, you will see it.
The MDS site is:
I don't see a .61 there, just a .68 and a .58, which are ABC.
You can contact Horizon Hobbies, the importer to the USA, through that web page.