Well I have never been impressed with the ruggedness of the frame on my 4400. I was cutting wheat 4 or 5 years ago with it, and every time I pulled back on the lever to slow the machine down to turn I kept hearing this clunking sound. I got out and checked to see that was going on, and the variable speed drive was hitting the tailings elevator. Where it bolts onto the frame the metal had just cracked from metal fatigue and the variable speed drive was about to fall off. I welded it back on, and re-enforced it with a piece of angle iron, and it has never been a problem since. The little triangular brace where the back end hooks on cracked on both sides of my combine, and had to be replaced. The adjustable rear axle also cracked at the top on both ends. My machine is not a junker that has been abused either, I know the guy who had it before I got it, and it was owner operated and well maintained, I have always run it myself and kept it up as well. It is more than 20 years old but, if I pulled it out and turned the pressure washer on it, it would look brand new.