im butting a b&m holeshot 3500 and a TCI flexplate in my LT1 and th400 combo,what size bolts do i need to bolt the TC to the flexplate?

 

Normally a M10x1.50 is used but it would depend on what the manufacture uses on the converter. Some th400 converters do not have threaded pads on them and there is just holes. At which point a good grade 8 bolt and nut would be used. Vince