I have a factory 71 383/727 from a 71 Satellite and I want to order a new a converter but I am unsure of which bolt pattern this set up uses. I searched but it seems that there are a lot of variables and I wasn't able to find a definitive answer. The combo is altogether and in the car so it's a little hard to measure accurately. The motor was a 2 barrel motor if that makes a difference. The auto parts stores show both flexplates for the year and model. Thanks