I've got the service manual to the Zenith DT2 display (includes a linear
PSU); dated 1979 and identified as part of the D12 series of monitors.
The HOT is a Zenith 121-1039, which, according to NTE is replaceable by
NTE 379.
http://www.vetco.net/catalog/product_info.php?manufacturers_id=14&produ…
Dunno if that helps or not.
--Chuck