Every year for the last few years, this site gives out about 1,000 different sound effects that they normally sell on their website. If you have space for 30 GB or even 90 GB, because I believe the 2016 and 2017 packages are still up, and you need sound effects, but you are looking for something very specific, go ahead and download these packages, and sort through about 1,000 files per year package.
http://freeassets.net/30-gb-of-free-sound-effects-from-sonniss-com/