1973 340 flexplate

B & M used to make one for the 904 for the 73 340, no longer available unless you find one used. B & M makes one for the 727 that is a little bigger but also works on the 904, it may require a little grinding on the nose of starter. I used one with a newer starter, 94 5.2 ram or Dakota, and have no clearance issues, B & M part number #10235