CH613 hop/shake

Hey guys, I have an 03 613 day cab that started to develop a shake in both the steering wheel and seat. Brought it into a commercial alignment shop and they went through the whole thing. Removed axle shafts, inspected and greased drive shafts, checked alignment on the whole system and adjusted air levels. They said it should probably need new tires, so I went and ordered 10 new tires, Hercules to be exact. I know they’re not Michelin’s/Firestone’s but the truck also only runs interstate. And we’ve always had great luck with them. It was better, no shaking or hopping but now recently it has been doing it again. I guess I don’t know what it could be, when I look back I can see the back axle hopping when it’s over 60 mph, loaded it’s more worse, empty not as much but it’s still there. I can feel it in the seat and then see it on the mirrors. The only thing I can think of is either taking the steer tires in to get balanced, or purchasing Centramatic balances. Unless it is something that is internal. Any help is greatly appreciated, I’m 23 and getting into hauling and it sucks having to pay $100+ an hour to figure out a shake and getting nothing resolved. Thank you!