I thought that I'd add my two cents worth to add to the confusion. In 1997 I bought a set of battery cables for my convertible. I bought them from a guy that had 100 sets specially made using the same manufacturer and the same "blueprints" that built them for Buick in 1965. I paid $100 for them but was very pleased with the quality, etc. They even had the part # printed on them, # 2989274 for the positive battery cable. Yes, they had the clamp type ends on them rather than the spring ring style. Yes, he sold them all.
In my 1965 Buick Parts Numbers Book, it has the following written; 4000 Gran Sport H.D. BTRY. & CLAMP JOBS #2989274. If you look in the Gran Sport Supplement Manual, page 10-4, illustration 10-1, it shows clamp style battery cables. So I thought that I had it correct. However, when I had it judged at the 1999 BCA Nationals in Columbus, Ohio, they deducted a point for having the wrong style battery cable, they indicated that it should have been the spring ring style. Go figure.
John