I have shipped several amplifiers and I also know something about UPS... Here is what experience has taught me.
IF the tube is securely clamped in to the final cage I would ship the amp with the tube installed. The tube is subjected to MUCH less abuse when done that way. Some amps don't lend themselves to that however. The Ameritron AL-1500, for example, does not support the tube firmly enough. Some amps have much more secure mounting and certainly any amp with breech-block sockets should be safe.
In my work as a private jet pilot I have flown reliever flights for UPS during times when they ran out of capacity. I have been to their sort centers. I would never ship anything remotely delicate and/or valuable through UPS. Their sort centers are a study in chaos and abuse. There was a time (years ago) when a UPS package was handled like eggs. Employees found throwing packages were disciplined. The union and the push for volume took care of that a long time ago. UPS now has a different approach to damage and claims. They have a web of rules (that they don't really tell you about ahead of time) you have to follow in order to qualify for a damage claim. They'll happily take your insurance money alright, then when your item is damaged you are directed to service reps who's job it is to discover where you broke the rules so they can deny the claim. After a long and bitter fight with UPS I finally had a rep admit to me; "UPS pays us to deny claims."
Here is how their sort centers work... boxes travel at a relatively rapid rate down long conveyor belts where they are diverted to to the proper bay where a container is waiting. These containers are something like 20x10x10. They sit about 15 feet away from the conveyor belt. There is one big guy at the conveyor and one inside the container. The conveyor guy takes the boxes and THROWS them in to the container so the other guy can stack them. This is going on at a rapid rate and there is never a pause to read "FRAGILE" stickers or anything else. They fill the container from bottom to top. If your box is on the bottom, tough luck, if it's on top, you're lucky. Boxes that are too heavy to throw are shoved, rolled, carried in to the container. A nice new Eimac tube, believe me, is tossed through the air like a football and lands on the floor with all the other boxes. If that tube is inside the amp it will be subjected to much less mechanical shock than pranging on to a steel floor after being airborne for 20 feet.
There is another danger to big items.. these conveyors wind their way through the centers sometimes getting to heights of over 10 feet above the floor. They have no railings on them to prevent something from falling. I've seen big boxes fall to the floor and bust open... peanuts going everywhere. Then a few guys take it, stuff as many peanuts as they can quickly shovel up back in to the box and wrap it with layers of tape and put it back in the line. They never pause to check the contents for damage. That could be your amp. That was my friend's vintage stereo receiver chassis. It hit something so hard it severely warped the chassis and pulled the tubes out of the sockets where they subsequently broke. UPS denied the claim. By the way, I've also flown relievers for FEDEX... but only for their overnight service. It was not nearly as chaotic.
Enough about UPS... here is what I would do. Remove the transformer and ship it any convenient way. They don't damage too easily if packed and padded well. For the amp chassis I would either find someone with a FEDEX GROUND account and ship it that way, or via Postal Priority Mail. I would also ship the tube Priority Mail or Fedex Ground. I have shipped over 2,000 boxes of china and dinnerware via Priority Mail in the last two years and have had zero problems. They use much smaller containers than UPS and handle the product much better... strange as it may seem, it's true. The post office raised their rates so much last year that I switched to Fedex Ground. I've had the same good luck with them. However, Fedex Ground cannot be used by the general public, but if you know someone who has an account with them you can use it. You can get your own Fedex Ground account by going to their website and following the instructions. But I'm not sure it's worth it just to ship one amp.
I have shipped 3 large amplifiers in the last year or so by the above method. The only amp I left the transformer in was the AL-80... the big Ameritrons were shipped with the transformer removed.
I hope this has given some insight..
73,
Dennis
NØSP