Originally Posted by
service1010
How can I tell which version of (sigh) the Boeing 737-800 goes from IAH to PTY? I have looked at every version on Seat Guru until my eyes are crossed
Bottom line is you really can't. The UA App will tell you within two or three days of departure, but that is always subject to a last minute change.
SeatGuru is not reliable for this purpose. Don't pay any attention to what it says about particular aircraft on particular routes.