Obviously one of those tubes is a GE that's the brand. I am not sure on the other tube. If you're trying to assemble a matched quad you need to get them tested and see how closely their parameters match.
Please identify these NOS 6550s
[URL=http://img4.imagetitan.com/img.php?image=23_e1.jpg][IMG]http://img4.imagetitan.com/img4/small/23/23_...]
[URL=http://img4.imagetitan.com/img.php?image=23_ge1.jpg][IMG]http://img4.imagetitan.com/img4/small/23/23...]
[URL=http://img4.imagetitan.com/img.php?image=23_ge2.jpg][IMG]http://img4.imagetitan.com/img4/small/23/23...]
I am messing up trying to include pics here
[URL=http://img4.imagetitan.com/img.php?image=23_ge1.jpg][IMG]http://img4.imagetitan.com/img4/small/23/23...]
[URL=http://img4.imagetitan.com/img.php?image=23_ge2.jpg][IMG]http://img4.imagetitan.com/img4/small/23/23...]
I am messing up trying to include pics here