142mm is non-boost thru axle, 148mm is boost spacing if I recall.
It's still pretty common for DJ frames to use the old standards of 135x10mm bolt on hubs. I'm sure some have used BMX standards too, that being 110mm rear hubs I think.
I would get whatever frame had the right length top tube, and hopefully was compatible with the wheels I planned on using, or at least the hubs have axles kits you could change.
