Here's the page from the 1984 catalogue.
http://www.lansingheritage.org/image...pro/page09.jpg

Within a couple years Altec and EV were part of the same company, the Altec ER's were then discontinued and replaced by EV's labeled as Altecs.

The Altec is labeled ER-10,12 etc

The EV relabeled as Altec will be labeled ER12L, etc.

Different speakers but often confused.