Would anyone know the production dates for the Mango that was fitted with the 2nd generation Nirvana masts and furler? I understand that this rig is imroved over the first series. Also, as I am interested in purchasing a Mango, are there other major equipment or manufacturing changes during the production run that I should look for or limit myself to? For instance I think the masts mentioned above were fitted to 1987 boats and later. Your help and recommendations would be greatly appreciated. Thanks, James