Another issue..

Unless you drove for thousands of miles I don't think this issue caused metal in your transmission. When air bags are over or under inflated it throws off your driveline angle. That will cause a heck of a noise and vibration at certain speeds. Would take a good amount of time for that to transfer into your transmission and cause issue, I would think.

Still on you to make sure truck is in proper working order

 

Minor shavings are normal. I doubt you’ve damaged anything. Maybe put some extra wear on the rears, from spinning them. Sure way to burn them out real quick. Doesn’t take much. Anytime there’s grinding in the driveline, first thing to check is ride height. Too high, grinds while accelerating, too low grinds while decelerating. Any Mechanic should know that. The grinding noise sounds much worse than it actually is. I would forget about it. Now you know. Easy to adjust leveling valve. Need to have the proper spec measurement. Sounds easy, but not always. 5 questions can result in 5 different answers. Once you know the proper measurement, you can check it anytime, yourself, and adjust it accordingly. I set mine, bobtail. Then check again hooked to a heavy load. Should be the same. A bad valve will often cause it to ride lower when loaded. Rides fine bobtailing. A sure sign a valves not working right, is if you drop a loaded Trailer, properly, with landing gear about 2” off the ground, and when you go to hook it empty, the landing gears suddenly too high, and needs to be lowered before hooking. They can be tricky. I’ve often had to reset mine a few times before it measures up right. Sometimes being convinced it was worn out, only to get it set right on one last attempt. This is why you should do it yourself. Might be simple, one time, a pita, other times. But you can take the time needed, to make sure it’s done right, and that it holds the setting. You should be able to look at the air bags, and tell if they look high or low. Good habit to have.

 

I talked to the service department at a KW dealer one time after purchasing a replacement level valve from parts for my AG380 asking them about ride height specs. They were nice enough to print off the page or 2 of drawings and instructions for measuring, where, how much, etc when setting the ride height. I kept those papers in the glove box of that truck. For some reason level valves on that truck never lasted more than a couple of years and I replaced several over the 10+ I had it. Setting ride height is really easy to do and you don't have to be a mechanical guru. Just requires a level parking spot, tape measure, a few small wrenches and the ability to read/follow instructions from the spec sheet.

 

Best trick I’ve found, is cutting a piece of cardboard, using it as a gauge. Setting on my Freightliner is 2.50”-2.75” on right front axle bump block to frame. I shoot for the middle, using a 2.625” Piece of cardboard, as a gauge.

 

We need more info! When they replace airbags you can remove the leveling valve to adjust ride height to get the bag off easier and on easier. It takes awhile to ruin a transmission. A lot of leveling valves now a days cant even be adjusted they are 1 single rod with 2 small bolts on them. Also unless u told them to check the leveling valve why would they? Did you complain about a bad air bag or bad leveling valve?

 

Leveling valve is an Achilles heel of Volvo trucks. I am so accustomed to the grinding sound that it startles me not when it snaps. Driving some may be worrysome but I never ruined transmission.
When I get to a safe place, I quick fix it with a tape or something like a zip tight or wire and fix it better once I get a replacement. It should be a spare part to carry with...but what shouldn't be?