My first rig as a General was a Viking Invader, which had 6146A finals. I
do remember backing off the drive just a bit from max power, I don't think I
ever replaced the finals in that rig which I used for six years.
I then got a Hallicrafters SR-400A, which used TV sweep tubes as finals, I
think they were 6DK6 and you couldn't over drive those without serious
damage. I remember having to replace those, and one of the tube envelopes
had partially melted.
Steve, K8SP