238 or 330 head for a K. Great little machine. the 250 GM motor goes through gas pretty quickly(tank a day) It will shell corn through the machine faster than you can shake it out over the chaffer and sieve. Easy to work on, most parts still able to get. Simple, well designed, that is why there are so many of them running out there...compared to any other brand. My young son runs my K, that what he likes. We have an F3, K2 and a K......like them all! lot of expert help on this site...... just ask.