Thanks ahead of time for taking the time to read my post. I have a few questions, so thanks for your patience ahead of time. So I recently receieved a used John Deere walk behind mower from my uncle, who is a retired John Deere sales rep. He built the mower for me. From what he told me, the mower is a mixture of the sx,sb,and se models. The deck is grey in color, it has steel wheels.... but I dont know how to determine what kind of engine it has? Any ideas? My main question is about the transmission. The mower works great, but I cant seem to find 4th gear. 3rd gear is too slow, but 5th is way to fast. When I move the lever upward, it moves right past 4 without any movement whatsover. It is my guess that 4th was the most popular gear in the mowers earlier days, thus possibly being warn out. But, is there something I can do to fix the issue? Is my only option to get a whole new tranny? I would rather not get a new transmission, but the slow/fast thing is getting a little old. Help!