The Tektronix 014-002 (aka 014-0002-00) is a mounting frame for the 160, 160A, 161, 162, 163, 360, FM122, and/or FM125 modules. It holds up to four modules.
The 1973 catalog mentions a one-unit blank panel, part number 333-0157-00.
Tek 014-002 in 1960 Catalog