Have you watched season one yet? If not, then here is a brief description of season 1 episode 6, which will leave you with lots of questions.
Leaving the tractor as it is, he heads towards the bar where he plays pool all alone and picks up a song on the jukebox.
May arrives at the site when he goes back to the tractor.
In the evening Gaddis and Gaddis #2 exchange words and came to know that by fixing the tractor Gaddis ended up in a parallel universe.
In the morning, they try to fix the tractor so that Gaddis can go back to his home, but they fail.
When He wakes up, he finds Gaddis #2 sitting next to him with the letter on the tabletop.