[Volunteer]

There is a really nice reusable rubber gasket available from Mopar.

And, other materials depending on company - - but don't neglect the integrity of the pan surface - as dana44/mr. k pointed out.
I like to use Gaskacinch to attach gasket and seal it to the pan but with more flat surface available on tranny, it is perfectly fine to leave this portion (and gasket itself) clean and dry - as the 'entry-level' cork-rubber gaskets will seal well. Suggest to re-tighten after first 'test-drive' once everything well warmed-up.