Trumbull was the original maker of what has now become the GE brand. GE didn't make switchgear and panels in the early days, so they invested in and eventually bought Trumbull. I've seen many Trumbull brand split-bus circuit breaker panels that legally accepted GE breakers (according to the label). They were probably early 1960's vintage panels based upon the age of the houses where I encountered them.
I just changed one out at a house in a "model village of the future", a joint venture between GE, United States Steel and CelloTex, known as Sterling Park, VA. These homes featured steel framing, energy saving and siding products, along with state-of-the art electrical products made by GE/Trumbull. These were total-electric affordable homes, with anything electric (including appliances, the water heater and furnace) being the GE brand. This development was built in the early-mid 1960's.
The panel that I replaced was fine and in untouched condition, but a home inspector insisted that it needed to be replaced. I'd have left it in place if this had been my house.
I don't know about today, but I think that a lot of GE's products were (are) made in GE's plant in Plainville, CT. My house was built in 1992 and my 200 amp panel was made in GE's plant there.
I've seen lots of Westinghouse gear in my travels as well, especially in Northern NJ and North Carolina.
Sorry for drifting off onto a tangent. This ends your history lesson for the day.