Rarest production model was the 800, followed by the 169, then the 126......
The mufflers are hard to find and expensive if you find one. The original 16 horse kohler was a 13 fin motor. Even if the muffler is gone and the engine is a replacement, they are still nice tractors. Price always depends on location and what the tractor looks like, runs, etc. Good luck and keep us posted.