'05 sierra with a bounce

bought an '05 sierra, 24k mi. that bounces pretty bad when i hit a bump at highway speeds (65mph). had it on the rack but found no unusual wear or sign of repair. was suggested it might be bad shocks. i'v had several gm/chevy trucks so i know what to expect and this is new.
any thoughts or suggestions would be great

I own a 2004 that is having same problem, just check it on the rack. No tire ware issues but still get a bounce and noise when I turn thr truck or hit a bump. Any thing like that

24K is low mileage to have bad shocks but they are 3 years old.
Remove each shock and compress each one. Just hold the bottom of the shock with both hands and push the top into the ground compressing it.
Now release it from the ground, still holding the bottom of the shock, and see if it extends fully.
If it extends back out to full length, then the shock is O.K.
If it stays compressed, then the shock is dead.