SB flex plate bolts

The race converters use the same thread and size as the flex plate to crank bolts (and they are 7/16 fine thread grade 8 bolts), but the heads are even thinner. I've ground the heads down on flex plate to crank bolts to use for converter bolts before.

It's really time consuming though and can be dangerous if you don't have a way to properly hold the bolts so I don't suggest doing it this way. If you do, you do so at your own risk.