Could not find any in 1/100 but this site
http://www.dc-3.co.za/dc-3-c-47-models-plastic-kits.html gives 3 AC-47 in 1/90 but I have no idea if they are still in production.
Monogram PA148-150 Douglas AC-47 Puff The Magic Dragon 1/90 scale
Monogram PA148-150 Douglas AC-47 Puff The Magic Dragon alt 1/90 scale
Monogram PA203-130 Douglas AC-47 Puff The Magic Dragon 1/90 scale