I haven't taken the cranks or bottom bracket off to check threads.
The pedals are KKT (Japan).
I took the back wheel off to get a better look. Something very interesting is stamped on the inside left rear dropout.
Saw this bike on the barter section of Craigslist back in 2014. Made a deal and got it. The fellow said he got it from a home that was being sold. It was in the garage. He repainted some of the parts.
I only ended up keeping it for a few months before trading it in for a road...