Trailer has a shake/bounce at 60mph and above

I have a 2008 Quad Axle Livestock Trailer that has a shake/bounce. When loaded it’s most noticeable when I reach 60mph on an incline. When empty it’s most noticeable reaching 70mph. I notice sometimes if I’m going 65 and I start coming to a coast that it’ll have the same bounce. Also noticed sometimes when I slow down for something it’ll do it when slowing down fast ( Using my jakes or using the brakes ) . When it shakes/bounce it’s usually does the opposite for 3 seconds then stops for 3 seconds , Trailer has been in the shop for this and can’t seem to get it figured out. Just had alignment done and axle bushings replaced . It’s 100% the trailer. I’ve hooked up to 4 other trailers and problem only exists with this trailer.

 

Shocks replaced 5 months ago. Back axle is a lift axle but not steerable. Tires keep wearing out no matter how many times new ones are put on. Do full axle when doing tires. Cupping/shoulder step wear/ depression wear . Tire wear Seems to be continuous no matter what

 

Yes sir

 

Tires are wearing on all axles. Trailer manufacturer is Wilson which is where trailer has been. I’ve gunna be looking at the hubs today. The more I thought about it last night that’s what I ended up thinking most likely the culprit. Will come back and update on what I find later this afternoon. Hopefully have an answer