I checked my parts books and see the same part number for the "A" bracket (2660401) from '66 through '70 all models, and '71 A-bodies only, regardless of transmission. They then show the "B" bracket (3467717) starting in '71 on B,C,& E bodies on all transmissions. I don't have the '72-6 passenger car parts books so I'm not sure how long they continued, but, by 1977, both numbers are no longer listed as current.
