It was me. My son refused to drive back to MN without a radio/CD, so I shipped a new AM/FM/etc out to GEV, and they installed it as part of the package, complete with new speakers to replace the moldy-oldies that were in the cab, and a new Tram antenna for the Sirius radio. It was nice in town, but on the highway, it would have required headphones, and the radio wasn't set up for headphones. We used the radio in town, though.
Since then, I cancelled the Sirius subscription - I'm not driving it across the country right now, and Sirius runs into money. I might get one of those transportable Sirius packages - the kind where the radio connects to whatever radio it's close to - in the future, or move the Sirius radio to the module instead. I've also thought about installing radio speakers behind the driver's headrest. Right now, they're in the cab's front corners, and the distance doesn't help intelligibility.
I suppose soundproofing was never a big concern when these trucks rolled down the road with a siren screaming, but soundproofing is a great idea. Don't do what a couple of characters in Wisconsin did a few years ago -- they decided to build a heavy wrecker, using every piece of scrap iron that was in the pile. The truck was an ancient Mack that was barely diesel. They grafted an elderly MIL-surplus winch onto the rear rails and connected it to a PTO, then made a wrecker A frame out of more scrap. They didn't complicate their workmanship by grinding any cut edges. They set up some winching ground legs using hydraulic cylinders with about a 3" ram, and the ground pads had gobs of weld for traction. It had an air-ride seat, but no air to the seat. Paint was never considered. They wanted to quiet the pig down, so they spray foamed everything in sight - under the cab floor, under the cab roof (no headliner to get in the way), under the hood, and the front of the firewall. The bank wound up with the creature, and asked a friend of mine if he wanted to buy it for what they had in it - we saw the foam in the cab and under the dash, we opened the hood (it took both of us), saw the gobs of oil soaked foam, and turned the bank down. He wouldn't even offer them scrap price - he figured if he tried to cut it up, the foam would burn for days.