Classic LXFF FF Fanned Flue Boiler, part number for a fan for this boiler?

The boiler is squeeling, which I presume is the flue fan assembly bearings.
So that I can send for the correct part, I need to identify exactly which boiler it is.
The model number inside, says Ideal Classic FF250, and also Classic LXFF & FF fanned flue gas boiler.
What is the correct identification?
There appears to be two fans that fit an Classic FF250.