Nikon did not say the Es were NIC but that does not mean they were not both mine look they are from the colour and abrasion resistance.
Originally Posted by Ricardo Miranda
The 5cm was a 6 element double Gauss 1,1,1,2,1 construction similar to its predecessor and successor Nikkors.
If you buy a series E 5cm on a FG-20 or EM in a charity shop you may get the package cheap.
Nikon needed the series E for the cheapo EM, FG, and FG-20 sales, but they still needed people to buy the AI-S Nikkors. The Nikkors were designed to ignore a high speed drive and 250 back day in day out with Teflon bushes on all moving parts. kuncka, kuncka, ... kuncka.
Don't try stripping an E unless you know how.