The one marked 374 is marked Current interrupting rating, 250 to 400
AMP ratings, 240volts 42,000 amperes,  480 volts 30,000 amperes & 600 volts 22,000 amperes. Circuit breaker frame  3 bolt union, issue A-855  600 V.A.C.  125/250 V.D. C.  Frame CAT NO. JL3-F400. See trip unit name plate for instantaneous trip range. The 3 settings are set on HI.  ITE Imperial Corp., Phil., Pa.  Label on bottom reads Und. Lab Inc. listed circuit breaker trip unit, issue A-485. Trip unit cat.no. JL3-T200. ITE 40C.

The one marked 377 reads circuit breaker 3 pole unit, issue KK-495, type ET, 400A  "JJ" frame, 40C.  CAT NO JJ3-8350.  Nominal inst. trip settings-LO 1900, 2  2300, 3  2700, 4  3100  & HI 3500. D.C. add 15% to nominal tolerance on all settings=10%. 

If you have any questions feel free to email me or call 315-649-2861. We will ship according to your zip. Thanks.