Just made an interesting discovery for the low budget 5.7/904 guys...

with the stock 5.7 flex plate you can use a jeep converter in your 904 or it looks like you could just knock the ring gear off you regular old 904 converter and use the 5.7 flex plate.

The flex plate I have is for an 04 durango 5.7 and has the same converter bolt bolt pattern and ring gear diameter and looks like it holds it within a fraction of an inch of the same position off the trans mating surface of the block.