This is a review of my 07 JD 3120. Overall its a great machine. Mine has the 300cx loader with 73" HD bucket, 447 backhoe with a 16" bucket, the larger R4 tires and 60" 7 iron mid mower. The tractor always starts right up even when real cold. Don't like how it jumps to a real high idle right off the bat being stone cold. It does that until warmed up.
The loader picks up a ton of weight, but I have had a problem getting the bucket cutting edge level. The backhoe works great and I love the curved boom over the 48 hoe on my old JD 4300. The bucket capacity on the 447 hoe is quite a bit less than the 448 at least bucket depth wise.
The mower cuts great. I put it on at a later date. The dealer and I set it up and it mowed like a golf course mower. After taking it on and off a bunch of times I can't get it set back to the same cut but it still cuts great.
For the size of this machine and it's about the furthest thing away from a dedicated lawn mower-it really does a great job! Wet ground still can be a challenge because of the weight in terms of scarring up the yard.
The flaws I've experienced are: low fuel light will come on sometimes for no reason, tilt steering wheel won't stay locked in one place, both front axle seals and 1 backhoe swing cylinder leak a little, and it is a little underpowered. I notice this the most when running my 5' JD 513 brush hog.
JD discontinued the 3120 probably because there were 4 identical models with a slight bump in hp each step. The 35 and 37s had turbos. I am old school and loved my 4300 without all the electronic mumbo jumbo. I couldn't find a mid PTO kit for it so I could mow grass so I bought this. It's a great machine, a few little flaws but no biggie.