It's simple. The crate motor uses a balancer with the depth dimension like a 440. As for the bolt pattern, older balancers had one bolt hole positioned different than the newer balancers. Some of the stock pulleys had one hole elongated from the factory so they would fit on either balancer. Other pulleys didn't have the elongation, and only fit one balancer. So as has been done for years, rotate the pulley till it lines up with all the holes, and if it doesn't line up with one, elongate it a little, and it will be just like the factory pulleys that came that way.