I filled out the Contact Us online form last night asking how to select seats.

Just took a look of the reservation, saw on the 339 we were assigned 3E 3F, and on the 321 we are given 3C 3D.

No idea a 3E and 3F position on the 339. I wish there is a seat map for 339 but on TAP site, it has no seat map of any kind. At least I dont know where to find it - after checking all possible tabs I could not find any seat map for any of its plane.

The 3C and 3D on 321 I suppose is the aisles. The 321 sucks but not much we can do about it as this is TAP's shorthaul plane,