[bash] How do I rename the extension for a bunch of files?

Similarly to what was suggested before, this is how I did it:

find . -name '*OldText*' -exec sh -c 'mv "$0" "${0/OldText/NewText}"' {} \;

I first validated with

find . -name '*OldText*' -exec sh -c 'echo mv "$0" "${0/OldText/NewText}"' {} \;