If its not the oil pump gear You may want to look for a thrust bearing problem. I just went through this on my SB duster, it has a 904. You might run your car and check the line pressure . The thrust bearing can be chamfered to help but I've also installed a restrictor to reduce conv pressure. A dial indicator can be used in car to check crank end play and help diagnose the problem. My end play was about .018. If it is your thrust hopefully you're cranks not hurt
