Anyone have experience with train nr. 51 from Phitsanulok to Chiang Mai ?

Hi,

I would like to hear from someone how the trainride is on train 51 from Phitsanulok to Chiang Mai. I have been looking at the website from railway.co.th. but I get confused. They say there is an option of seated, airconditioned second class bogey and show a picture of rows of seats like in an airplane or bus. People are not facing eachother.
But if I look at Youtube clips I see no bogeys that have seats like that (always facing other passengers) and when I try to book seated & second class, then the A/C option seems not available.

Does anyone know if a airconditioned, seated, second class exists on train 51, and if so... maybe have picture of how it looks like ?