Help with two Classic tester's

I picked up two testers and need help finding info on them. One is a black UART tester made on metal and is 14"x10"x6". On the top panel are all the switches with large labels such as INTERRUPT INPUTS, DISCRETE INPUTS, and REU ANALOG INPUTS. These are the smaller labels under each switch D.GND, WRITE/READ UART A REGISTERS, PWB CONNECTOR, WRITE/READ UART B REGISTERS, VIDEO SELECT VSYNCA/VSYNCB ON, LOW VOLTAGE ALARM INPUT ON, WR/RD, EOC INTERRUPT, ACD INTERRUPT, UART B INTERRUPT ON, UART A INTERRUPT ON, PWB DC CURRENT (+5V), RESET, COMPANSATION DISABLE, SELF TEST REQUEST. REU/DU HOT, VREF/VS, and 0.012/0.25/0.50. On the front panel are a power switch with selects for INTERNAL or POWER SUPPLY SELECT, MAIN POWER ON switch with red light. On the back panel we have a 25 pin connector, External Power connectors +12, A.GND, -12, and +5, a Fuse, and plug for a power cord. There is no ID labels anywhere on this black box. Any leads? The second tester is a Field Test Unit for old tape drives made by Magnetic Peripherals Inc. part of Control Data. Has equipment ID of TB303A, Series code of 11, PN 75255003 and is this thing every heavy close to 50 pounds in a special carrying case. Any help on this one? Thanks in advance.