The following ponies are NC marked..... it is variable though!
Greek
Argentina (some ponies can be marked Argentina)
Colombia (some are NC, others are marked, they can be found with an Italy stamp)
Venezuela
Spain (some are marked Spain)
Mexico (only some of the CP ponies will have a mark)
Peru (some are marked some are not)
Some of the above mentioned countries will have no stamps at all on the feet, some have variations on PAT PEND *date* Hasbro (c).
The marks can look filled in scraped away or blobbed over. Some can look badly done, almost like they have been tampered with. On some Greeks the original Hong Kong can still be seen.
I hope this helps.
Love pkw xxx