Turkish Airlines Miles&Smiles - Equipment types

I am sure this question has been answered before, but I couldn't find one looking through previous posts.

For several of my scheduled flights on TK, I see different equipment types posted on the TK website from what I see posted on Expedia, Travelocity, etc. TK might say A330, while the others say A340. Or TK might say A321, while the others say B738. Which source is likely to be more accurate?

The one which is at the gate when you actually board the flight. They change the equipment all the time which suits better to the given day needs.

They cant even get consistancy across their own website: Their timetable says one thing; the flight details another and the seat plan another ; as above you only know for sure at the gate.

OK. TK website says A321. All others (including ExpertFlyer and Lufthansa seat maps say B738). I'll report what turns out in about two weeks time.

Well, here is the score:

Munich to Istanbul: TK said A321, other sites said B738, and B738 it was.
Kayseri to Istanbul: TK said A320, other sites said B738, and B738 it was.
Istanbul to Munich: TK said A321, other sites said B738, and A321 it was.

Overall accuracy score: TK 1, Other sites 2.