During the 1970s, JBL had four different models that use the same or similar drivers and cabinet. From left to right in the photo (in reverse order of their introduction) are the 4311, L100A Century, L100 Century, and 4310.
The oldest design is on the right, and each newer version appears to it's left. The 4310 and 4311 were the pro studio monitors, and the L100 Century and L100A Century were the commercially sold versions. They all shared the same or similar versions of 123A woofers and LE5-2 mid-range drivers, but had different tweeters, the LE20 in the 4310 and L100 Century, and the LE25 in the L100A Century and 4311.
The L100 Century had the vertical alignment of drivers, and had a crossover network of sorts:
View attachment 23326
My speakers that Dennis used to design his new crossovers were the L100A Century. They had a much simpler network:
View attachment 23327
I hope I got all this right and explained it clearly.
And finally, Dennis's new crossover for the L100A is fully described here
https://forums.audioholics.com/forums/threads/the-vintage-jbl-west-coast-sound-becomes-the….25014/.