Well, the
PDP8/e has 2 rows of lights (Address, Data) on the panel
too...
Or is that not what you meant.
I'm familiar with the 8/E, I have one (and a LAB-8/E, too). This has
more rows of lights than an 8/E,F,M. I don't have it in front of me,
but I'm sure it had like 4 rows of lights (like an 8/I,L) and no
rotary switch.
It could be what's referred to as a MARS (Memory Address and Register
Status) panel.
The only one of those I've ever seen was at our PDP8 FS lab in Parker
Street.
It's a full-height rack panel (same height as the 8/E) with several
rows of lights for PC/AC/MQ/etc.
-Rick