Where on earth can I find an internal 67mm 1.0mm pitch lens adapter?

I know this is a thing that has to exist - I just can't find it! I've got a super obscure bit of kit that has a 67mm thread with 1.0 pitch. The thread is on the outside so I need a "female" adapter. It can be adapted to whatever, honestly - as long as it's easily adaptable to a standard mount - M42/T mount is great for versatility. It's really tough to search for as all I get is listings for 67mm filter thread macro adapters. For reference, most filter threads are all 0.5mm pitch.

Figured you folks might know a better place to look for specialized adapters like this. I would rather not get it custom machined or anything since that would be a very pricey solution. Sorry for the ramble this has just been driving me crazy!