to be 100% correct, ALL the aircraft are now operated by Thomsonfly, First Choice Airways Ltd doesn't lease any aircraft at all, they were all transferred to Thomsonfly last week.....but as TUI says from 1st Nov everything is TOM designator, if looking at a brochure then TOM = old Thomsonfly and ToM = old FCA. However, from 1st May 09, all the crew will be integrated, the service will be the same etc etc so at that point impossible to tell unless you have access to the flying programme.
I did hear that most of the cruise flying was destined to be on ex TOM premium config B763ER and most longhaul TUI package flying was due to be on ex FCA B763ER over this winter...not seen if that's happened yet tho