6500 was an OK machine, the 6700's were better on power and ride.  You could put a boom accumulator from a 6700 on the 6500 which helped, but still would not be as smooth as 6700.  With that said,,,, it does NOT have suspension on the rear axle so don't expect it to ride like a Cadillac.  Michelin (radial) tires on the back do help the ride as well.