The Pro Products balancer came with three seperate weights,that you can install depending on your application. I installed the weight for the 360 Magnum.
Hopefully the balancer is a good one, otherwize if your useing the stock rotating assembly, just use the stock magnum balancer & stock flexplate that has the factory weights on it, all you'll need to do is "longate" one of the hole about an 1/8", then your good for a "N" balanced converter, I opened mine up to except the 7/16" bolts. B&M used to make the flexplate for the 360 mag/904 conversion, but they discontiued it last year.