Onan 5500 generator from that era have 2 mufflers, the exhaust pipe connects directly to the second muffler. The Onan parts list has both the rear(which mine does) or side which yours does. It really is quite easy to look and see if the pipe is bent/damaged or the muffler is damaged.
To really see anything of the muffler, you would need to remove the generator. Google the service manual and you can tell what the parts look like.
On mine, the exhaust pipe mounts directly to the muffler and the threaded holes in the muffler's flange are perpendicular to the axis of the chassis, but mine is a rear exhaust. I believe yours will be the same but the exhaust pipe will have two bends while mine has just one.
My 5500 has four mounting bolts to mount the generator to the MoHo, one two on each side in the corners.. When it was removed the tech used a pallet jack and supported the generator and removed the four bolts and dropped the generator straight down. Oh yeah, he removed the exhaust pipe, gas line and electrical first.