I've noticed that the handful of normal bt30 tooling with pull studs that I've collected hasn't been long enough to engage with the drawbar. Did dyna myte make its own proprietary pull studs or are these just really obscure obsolete ones used?

So far I've collected about 20 nice tool holders, I'm hoping to find some cheapo Chinese pull studs so I don't have to spend another grand on tooling.

Is there a pull stud model or critical dimensions I can search for on ebay to get some that work?

Is it possible to change or modify the DM2800 draw bar to accept more commonly found pull studs?