Hi Daren,
As far as I am aware, all the Mark series chainguards should be interchangeable - only the Plus series was different, in that the mountings were moved to give more clearance on the chain so that larger sprockets could be fitted. The only detail difference with the early T35 chainguard was that it had the fittings on top for the tyre pump. Maybe your rear subframe has been bent - from memory, the bump stops should not land on the centre of the leg of the swinging arm but are offset to the outside - perhaps even overhanging the side slightly.
Regards,
Eddie.