I found my own answer. My "good" followers are the latest version (as far as I can tell) and are marked with the # 5 on them.
Here's the history of .40 Glock hi cap followers if you care:
"If you want the latest follower, it is part # 1028. They go like this (earliest to latest).
.40
1028, .40
1028, .40, 2
.40, 3
.40, 4
.40, 5
Bases for nfml 9/40 mags is #455. Insert is # 5166.
Bases for fml 9/40 mags is #3206. Insert is #5166 (same as nfml)."