Ok I've got the motor, it is a genuine Hoover motor with part number 43174-668 HD28. Just realised that the plastic is cracked on the side where the motor cooling fan is. Sure it won't affect performance.
That's a later one - either 575w or 600w. You can tell by the white plastic fan housing. This is what made the later models uber loud as the plastic on the motor was so thin compared with the older ones.
Yeh, The later ones had the white motor casing. I once had a Turbopower Total System U2798 from 1995 that was 430-450 watts and that had a white cased motor, it wasn't loud either.