360 magnum flexplate?

Just get a stock 5.9 flexplate. One hole will need to be opened up about 1/8 or so, not much. Use a neutral balance converter which you should already have. I have a 1994 5.9 and it had a 318 flexplate but a weight on the converter. Several at the juslnkyard were the same way. So, I think you need a 1996 and newer flexplate. I bought mine brand new at oreillys. Advance auto had them much cheaper but oreillys price matched.