GW76, yes - the 757 is available with extended range features but not all of those need/have to be present for the aircraft to fly long distances. Is a 757ER an ETOPS aircraft, a high gross weight aircraft or both - there is no such spec.
It is interesting that everyone appears to be assuming that 757s would be destined for Leeds. Has anyone considered that yields ex Manchester on the Jet2 services might be so low that they need an aircraft which can produce capacity more cheaply than a 737-300, and Manchester might just be a potential home for the aircraft? Just playing devil's advocate - I don't know anything more than anyone else, but I had heard that the low yields at Manchester had been a bit of a shock versus what they were used to at LBA.