It was the first 1500 larger Boomers with Hydro Trans. There were instances of jumping out of gear when going down hill with a load on the tractor. The deadline to have the repair made was 8/31/01, although I am sure they will be contacting owners who have not had work done. I received a letter on my TC40D. If you are the original owner, you would have gotten a letter by now. Transmission has to be torn down and a gear replaced.