13 fishing Concept C

Just purchased 2 concept c reels. 1 7.3:1 and a 8.1:1 but have a question. The side plate on the 8.1 comes completely off and the 7.3 has the spring bar that holds the plate on. The 8.1 has a solid black box and the 7.3 has a black/grey box. Reels look, feel, and cast/reel the same. Was just wondering if 1 was a newer version that the other. Was hoping if someone knew that might be using these reels.

They do feel awesome for sure!!

The one that comes completely off is a gen 1 the other is a gen 2

Perfect. All good to me. Thank you for the info!!