I have a Mesa Boogie 400+ Bass Head that I am not using anymore. And I am selling it to fund toys of course.
In 2010 it was gone through by Tim Pinnell of Top Gear Guitar in San Diego, Ca. and given a clean bill of health. He said the tubes look to be original. They are Mesa Boogie 6l6 Power tubes.
I had just taken the taped invoice off the front of the amp before the pics. So that is scotch tape on the front.
Bass sounds great and has enough power to shake the house. If you know Mesa, you know this is a great amp!