How much does the BODY without Frame Chassis of a 60 passenger school bus weight?

Depends. Just the steel weighs approximately two tons. The floor is usually 3/4" plywood with rubber covering, the Windows are surprisingly heavy. The seats must be added in too. If you were looking at lifting a complete body including the firewall and windshield minus the frame, running gear and drivetrain, allow for about 3 tons.

The frame weighs about a ton, the rear axle and suspension about the same, wheels and tires are probably 200lbs each. The nose and core support are heavy too, the front axle with suspension and steering probably more than half a ton. A decent diesel engine would be 1500 lbs, a smaller one about 900 lbs, transmission with adapter plate from 350 to 700 lbs. Not hard to see how it quickly adds up to a bus that weighs around 8 or so tons.