I'm playing version 1.72.2, and just purchased a Mussurana which had a Naval Energy Unit (NEU)- problem is, that once I had purchased the craft, the NEU did not show in my equipment list.
To double check that I hadn't accidently purchased the wrong ship (ie one Without the NEU), I went back to a previous save file, and purchased the ship again - the same thing happened! (has certainly charged me the 1005000Cr that it costs for a ship with this upgrade, too!).
I also tried purchasing a Cobra with an NEU to see if there was simpy a bug with the NEU being recognised, but on the Cobra it was present on the equipment list

Spent hours saving up to get this ship, so a bit gutted! Any ideas?
Cheers guys