The WLR8 is the older ESM system and is very similar the the one that was installed on some carriers. Minus jamming and such. The newer more digitally enhanced systems were the WLQ-4 (Sea Nymph) for the 637s relacing the WLR-6 and the WLQ-10 replaced the WLR-8 on the newer classes.
This tells you about as much about it as I could tell you without getting shot.
http://www.lockheedmartin.com/data/assets/1018.pdf
Rip