If they're the same as a '51 Chevy 216, the stud on top of the starter mounting would be 1/2-13-20 x 1-5/8" (double ended=13-NC + 20-NF thread) and the bolt on the bottom would be 1/2-13 x 1-3/16" (NC thread).
Last edited by Gdads51; 01/26/2024 4:14 PM. Reason: add detail to dimensions
