Hi Daniel,
That's a z1055 from 1988. The z1055 and z1065 were the first of the "Turbo2" branded cleaners and originally the last of the 500/Twin Turbo style. They were sold alongside the 614 and 616 uprights and were discontinued in 1990. That style was brought back in 91 as the even-more-budget/basic z1070, which ran as the Lux's budget upright throughout the early to mid 90's.
Great cleaners, although the 1055 and 1065 always seem to yellow a great deal more than any other Lux I know of. They work fantasticly though. If you can find them, have a look for a set of replacement brush strips for the roller, which will massively improve performance.
Chris