Mopar made only 2 flex plates for the stock 904 tranny cars that I have heard of or seen, that being said they where 11.0 inch converters with 5/16 converter bolts the smaller 10.0 with 5/16 bolts.
On your deal your probably going to need a Hi Po 727 6 bolt crank pattern for either the 11.0 inch pattern with the 7/16 bolts or the other one for 10.0 inch pattern with the 7/16 converter bolts.
B&M use to offer a solid universal 6 bolt flex plate with all four patterns on them, not sure if they still do and how good they are now
Good luck, Mopar offers the Hi Po 6 and 8 bolt Hi Po flex plate for internally balanced motors only with the single pattern for the race converters with the 7/16 converter bolt sizes in both SFI specs and non SFI specs
The converter size determines which flex plate you will need, not the tranny case
Cab, thank you so much for the very detailed explanation.
I drag raced this car 30 years ago. Used a B&M Super Holeshot converter with a 727 and standard externally balanced 360.
Parts were specific for it from what I remember.
Thank goodness technology has come a long way but this is one conundrum I couldn’t find a part “specific” for.
It looks as if the one the J Body posted below (Thanks J Body!) will be the one to use.
It’s the B&M #10230.
It is listed as Mopar V8 6 Bolt internet balance engine for 727.
So I’m assuming it will work with either Big or small block as long as it’s internally balanced?
And.....I assume it will work with a 727 or 904?
And it has the dual bolt pattern.
Thanks again guys.
Very helpful.
Wally.
