Rhett:

Since this thread is over two years old, it's highly unlikely that we have any manner in which to receive feedback from the original poster. In the future, it would be best if you start a new thread using the "post a new topic" feature at the upper-right hand corner of this page.

I can tell you that 327A is the nomenclature for the actual reed relay component and the 72K is the date/period of manufacture (1972 was the year).

Upon reviewing other cards of similar design, I found some of a later date of manufacture where this reed relay was marked 327L, so I'd guess that the Delta was meant to signify that the relay's part number was actually 327D.

There are no potted components on these cards except for whatever "mystery" component may reside within this reed relay. Since they were marked "Contents under pressure-do not open", most people took heed to this warning and never bothered to experiment.

Ed Vaughn, MBSWWYPBX