I'd be interested in hereing more myself. I just bought a new 5220 4WD after parking my butt on both tractors. I started both, found the 5220 to run much smoother (don't ask me why the 5105 vibrated like it does) and it just felt much better to me. Also, I hooked the 5105 in low gear, ran it up to 2000 rpm and was surprised at how fast it was......too fast. The 5220 just crawled in comparison. At any rate, I spent the extra $3300 and only time will tell if it it was worth it. Don't know what kind of deal I got either. The 5220 4WD has mid and rear SVC's..2 out the back, one on the side, industrial tires, front bumper, joy stick and synch-shuttle...$24,800.