I owned a early 4 Cyl. 4000 with the SOS for about 4 years and I liked the SOS. From what I've read, the SOS has lower 1st gear than the manual transmission. This is a good thing for Tilling as you need to just crawl speed for that. I wouldn't give up on the SOS yet. There are still some good service people around that can trouble shoot those transmissions and would be lest costly than a major swap of all the components that would be required. See who you can find to help you with the tractor transmission. bjr