I'm flying SCL-EZE in March in J. ac.com says lunch is served. Is it possible or necessary to order a special meal (Vegetarian) on this route if it is a cold plate?

Also the seat map currently shows 1-2-2 seating i.e. not an XM aircraft. I'm actually a bit worried it might be switched to an XM aircraft at the last minute as I hate those seats for short daytime flights (but great for overnight flights) and it makes looking out of the window a sore experience. I hear the South American routes will be the last to see XM 767s so fingers crossed. What are my chances of getting an 'old' aircraft in mid-march?