Vintage Synth Repair

Hi folks,

I was wondering if anyone here could identify a Moog Modular module for me. Looking on the Moog Archives site - http://moogarchives.com/ - on both the 1968 and 1974 modular photos, there is a 3 unit wide module bottom left of both cabinets (two units in the 1968 photo) that doesn't seem to be mentioned anywhere and I can't find it on the Modules list either.

Anyone know what it might be?

Cheers.
Tom