I have not found a digital version of Stack, but there is a somewhat similar idea in Disco Inferno NF https://www.myfonts.com/fonts/nicksfonts/disco-inferno-nf/ Gleam http://www.fontspace.com/rosemarydesign/gleam Nomitais http://californiafonts.com/fonts/12547/nomitais and Chocobot Stacked http://californiafonts.com/fonts/592/chocobot%20stacked
Don

The closest to Face Photosetting's Stack is the font by Bright Ideas called Staxx, which was found by Ryuk.
Like Stack, Staxx has three layers, a shaded effect, and sharp corners. Stroke thickness and spacing between stacks are similar. Letter-forms for the capital letters are generally similar but the numbers are quite different. Major differences in the capital letters include the lack of a spur on _G_, angled instead of horizontal terminals on _S_, the curved stroke and terminal angles on _C_ and _G_, and the bottom stroke on _J_.
Comparison was made to the Stack specimen in my Letraset Product Manual. See the scan I posted in http://typophile.com/node/107360
Unfortunately, Staxx is unusable for commercial purposes because it is an orphan font by a defunct company, and there does not seem to be any legal owner of the intellectual property in its digital fonts.
Don