2000 T600 bucking like a horse. Help!

Hello, Im not new to trucks but am new to Kenworth and the kenworth 8 bag system. (wishbone) Anyway, I bought this 2000 T600 about a month ago and the ride is horrible, especially loaded, (bellydump). It bucks like a bronco, to the point that the cab hits the hood. Ive replaced the cab shocks and the bags were new when I bought the truck. Ive lowered the bag pressure as well as raised it. Same results. After today, im thinking the problem might be in the suspension. When you hit dips in the road, seems as though the rear suspension springs up throwing the cab up and forward. In dash air bag gauge reads 65psi when grossing 80k lbs. Any Ideas? Thanks, Gary D

 

cab shocks are new. Im new to the Kenworth susp, but on the old columbias, it seem the rear shocks did very little. The rear susp shocks might be toast. Would this cause the bucking?

 

Thanks. Ill try that