I need to make an adapter for my Meopta enlarger to fit el-nikkor lens, which uses the standard M39 mount.

If I understand correctly, M39 enlarger thread is really leica "M39x26tpi" thread. But what kind of thread is that? Mixing metric and imperial standards? My dad who has some general experience in the threads area says it's 26 threads per 25.4mm, so it's actually just M39x1. So why is it reffered to as M39x26tpi at all? Is it OK if I just use a normal M39 thread?