I know enough to be dangerous regarding that little dozer. We own one in the diesel version
I'd be dearly tempted to buy it but no time this year to come get it. And come get it I would. Be a cool trip especially to work in a little hunting....
John Deere built that series of tractors with a vertical twin cylinder engine in Dubuque Iowa vs. the Waterloo Iowa plant where the more familiar horizontal two cylinder tractors were built. The DNA of that goes back at least to the model M which was available as a crawler and wheeled tractor. That evolved into the model 40, then 420 and 430 which the 30 series was the last and most advanced of the two cylinder gas versions. At that time, 1959 and 1960... John Deere was developing the "New Generation" of tractors of which surely the 4020 has to be the most famous and widely recognized. But they started with a 10 series, 110 lawn tractor, 1010 to replace the 430 and smaller 330, 2010, 2510, 3010, 4010, 5010 known as a Muscle Tractor but still 2 wheel drive and the rare 8010 articulated 4 wheel drive.
Back to the transition from the 430 forward to the 1010 which was available in a gas and 3 cylinder diesel (2010 through 3010 where 4 cylinder with 4010 and up being 6 cylinder). John Deere wanted to bring a small diesel tractor to market in 1959 but the 1010 was still a couple years from being ready. So the 435 was born when they bought two cylinder two stroke (like a chain saw) GM or Detroit diesel 2-53 motors and mated them to a 430 transmission and rear end, having to come up with a specific wide front end to mount to the GM motor (as the motor in the Dubuque tractors are the structure, there is no frame). And they used the 440 Industrial hood as it was wider to accommodate the diesel engine with that supercharger on the side (blows air into the pistons through those 2 cycle cylinder ports).
So as you perhaps gathered, starting with the M and continuing through the 40, 420, and to include the 320, JD painted some tractors yellow and offered a few other features such as special hitches and labeled them "Industrial". When they went to the 430 series, they came out with the 440 Industrial which featured a larger front hydraulic pump, wider hood, much heavier grill, heavier front axcel and options with an Industrial loader, backhoe, a crawler version with loader like this one the OP has and a dozer blade including a 6 way blade like
@Just Gina and I have
We also have 6 435 tractors.
Production of the 435 only lasted about a year and a half in the US. Roughly one per dealer at the time were produced. My dad bought the local one before I was born... that engine is perhaps the most unique sounding of any farm tractor.
My mother was a stary eyed teenager working as a clerk in the local grocery store when my then 19 or 20 year old father to be would drive that tractor through town. She told a story about how her heart would fluter when she heard that tractor driving past. She described it as "such a cheerful sounding tractor". And she would run to see my dad driving by in his mostly white T shirt
Grandpa actually bought a gas rubber tire 440 loader when we were kids and put a pallet fork on it to load logs in the woods. He was a lumberjack at heart but a farmer by trade. Probably a better lumberjack..... I owned that tractor for a while but foolishly sold it to neighbor years ago.... My brother owns the 435 along with a couple others and a 440 diesel on tires with loader and backhoe. I'm not sure when they discontinued the 440 but it may have survived a year or so longer in the all yellow version than the green 430 and 435. So the OP is correct in 1959, 1960, or possibly 1961.
John Deere did move the tooling for the 435 to Argentina where it continued in production for a few more years as a 445 farm tractor and was also available down there in a narrow front "tricycle" version. Much desired by a handful of people in the US to run in Tractor Pulls... and by me and my brother
So anyone from Argentina reading this, PM me of you know where I can buy a couple good John Deere 445 tractors with narrow fronts and we will conspire to have them shipped up here!