I believe it's a Noble only part (don't ask why!) So I doubt you'll be able to source from another parts bin. Maybe someone on here has one that they removed to save weight???
I have mate who's just started building small units for kit cars, just had a demo and ill be changing mine over winter as mine is so dodgy and its lightweight too ....
Does it have metal sides? If so I used to get my radiators done by a small radiator company, they were brilliant at refurbishing and I never had one come back.