from the other thread it seems a new thermostat can be had from halfords for about a tenner

Whatever you do don't put a stat in the car for a tenner, get yourself one from ford their about £40, while its out drill a small 2-3 mm hole in it because 4x4 stats are notourious from jamming shut, doing this will help if the stat ever jams shut by letting the coolant through, don't ever run a 4x4 cossie without a stat in place, stat housing is i think still available from ford front bit around £45 and back piece a bit more cost at around £140, changed mine recently, can't get the little bleed screw that sits in the front stat housing though so if yours strips its thread replace with a like item.

C L