1 NOS RCA TA-8474 2-28V 4A Adjustable Voltage  Power Hybrid Regulator with Data & Socket DF-263A . 8 Pin TO-3 Hermetic package. From their HC4000 series circuits. Application Note AN-6026. 

If you buy the 3 I will include 2 Unknown Other types marked 2949V Single & other one Dual. Sorry no data or info.