Chris, an extract from GTT from Brian's article on Tube Frame Bolens.
The Bolens Husky 600 did not come with a locking differential. A good way to tell if you have a true original transmission in your 1962 Bolens 600 is look at the hitch on the back. It will be a cast iron hitch molded right into the transmission. 62' was the only year they did this.
Another important thing to know is that in order to be able to push the tractor in "free wheel", you must pull out the cotter pin and slide out the free wheeling pin. You can see the pin in the area circled in the picture above.