PDP-6s at MIT

[Lars Brinkhoff]

I always thought there was one and only one PDP-6 at MIT.  The one
running ITS at the AI Lab.  But then I found a post to alt.sys.pdp10 by
Marc Crispin:

> I did meet the MIT AI and DM PDP-6s

Digging further, I found Project MAC progress reports mentioning this
Dynamic Modeling PDP-6.

Page 59 in http://www.dtic.mil/dtic/tr/fulltext/u2/732767.pdf

> at Project MAC, both the Multics GE 645 system and the Dynamic
> Modeling and Computer Graphics Groups' PDP-6/10 system are network
> hosts.

Page 60 in http://www.dtic.mil/dtic/tr/fulltext/u2/756689.pdf

> Work on the Dynamic Modeling System began, effectively, in October,
> 1969, when a used PDP-6 computer with 32K words of memory was
> delivered to Project MAC.

Does anyone know more about this PDP-6?  Did it ever run ITS, like its
PDP-10 successor?