Different battery post sizes?

My stock battery died a few days ago (~5 years & 90k miles). I looked in Consumer Reports and the first replacement I bought was a Napa Legend Premium 8435 (size 35, which is supposed to fit the LGT). The battery was a tad larger than the stock battery which I think was size 65, but the problem was that no matter how much I tightened the nut, I couldn't get the positive battery cable clamp tight on the battery post. It was snug, but if I pushed moderately hard it would rotate on the post. I always thought battery post sizes were standard, but just for the heck of it I returned the Napa battery and bought a Die Hard. With the Die Hard I got the clamp tight and it's working fine. I was surprised that there would be a difference in post diameter, for the same size battery (size 35) between Napa and Die Hard. My problem is solved and I have a working battery now, but I was just curious if anyone else has run into this problem before?

The battery posts on the stock battery do seem small. I replaced my battery with an OEM battery bought with Subiebucks, but that begins a different story. The new battery is larger than the (2005) original, and barely fits. In fact one corner is rubbing on the body cross member. Anyone else?