(quoted from post at 21:13:30 12/01/16) Not here to start a disagreement, but I am quite sure it is the 10.5 liter and 12.5 liter Deere diesel engines which share some resemblance to the 60 Series Detroit diesel engines. These are the engines with the overhead camshafts and 4 valves per cylinder, along with the high pressure fuel injection system under computer control.
There is a 10.1 liter engine, which is a "metric equivalent" to 619 cubic inches, just like the 7.6 liter is the "metric equivalent" to the 466 cubic inch engine. I don't recall a great deal about these, but the engines designated by these metric sizes were first placed in the 55 series medium and large frame tractors and also the 60 series four wheel drive tractors.
With respect to "bolting up" to your 5020, I am fairly sure it will. I seem to recall there were some various improvements/changes from the prior 466 to the 7.6 liter engine. The same would apply to the 619 transformation into the 10.1 liter.
Yes they would fit right on.
What I have found so far working on 6030s and 5020s.
You need hood, air filter, and exhaust elbow from a 7520 if you want your 5020 to look like a 6030.
The radiator has to be installed further forward, with shorter grill screens from a 7520, 6030 or 5010. This can be done by installing the 2 hydraulic pump cover plates from a 7520 that are almost the same than the 6030 (they bolt right on on a 6030 but needs to be extended 1 inch forward to seal properly). This will give you the right radiator location for the longer 619 or 531 turbo pulley setup.
Then you will have an issue with the remotes and air filter. Best thing is to convert it into a side console, using a 6030 side console if you find one, or just start from a common 2520 side console and remake the console support specific to the 6030, or put 4430 remotes on the back of the tractor with a custom "drill and tapped" 1 inch thick plate that would hold both remotes. That can be made in a clean enough way that it would look factory for someone not expert on these tractor.
Another way that does not look great is to either raise the air filter above the remotes (have seen hit), or put the air filter on the side of the frame. (I would never do that either)
A good idea is to not move the remotes and put a big air filter same way than a 4440 has it, like in this picture.
http://www.farmphoto.com/image.aspx?n=1860047a-8b8b-4406-bbe2-842fa2974776.jpg&s=original
This picture came from this topic:
http://www.farmphoto.com/thread.aspx?mid=561996&pgIdx=6
If you follow this topic attached. You will see all the processes involved with 5020 repower. As you will see, they did not move the radiator forward, so they had to make a new pulley, and they still had very small clearance to the fan. I think it is much easier to go with 7520 parts.
Last thing is that 7520-6030 motor has the rockshaft cover with the vent on the back, later motor has the vent in the middle. I do not think that it would create any problem with the 7520 air filter mount, but just in case, if you go to a salvage yard for other 7520 parts, I would grab that rockshaft cover at the same time.