I love that 6125R, but I'm passionate about these old John Deere's. Especially the 435's
John Deere was working on the New Generation tractors, moving on from the 2 cylinders. However in 1959 they wanted to offer a small diesel tractor but the new line was just not ready yet. So their answer became the 435, from the line of Dubuque tractors such as the M, 40, 320, 420, 330, 430, and the Industrial 440.
The 435 is basically a 430 transmission and rear end, painted green hood from the yellow 440 ( wider than the 430) and a two cylinder, 2 stroke, Detroit or GM diesel engine. (Both this diesel and a higher RPM, higher HP version of the 430 gas engine was offered in the 440).
They built approximately one 435 per dealer and built them in 1959 and part of 1960. So it is one of the rarer JD tractors and possibly the rarest diesel. They built fewer 330's which is a scaled down, cheaper, lower RPM 430. They bring some major dollars nowadays

We do have one of those as well as 430 and a 420.
The JD 435 is a very unique sounding tractor with that 2 cylinder 2 cycle high reving engine! It of course fires as often as a 4 cylinder 4 stroke. But the sound is unique and LOUD! LOL
The first tractor i drove without dad helping was a Farmall Cub. I was 5 years old. Shortly after that I was taught to drive the 435. My dad had bought the only one sold by the local dealer in Pierz MN. It remained the only brand new tractor he ever bought. I think he was 19 or 20. My mom was working as a cashier in the local grocery store while they were dating and commented;
"It was always such a cheerful tractor and had a unique sound,when I was dating Richie and worked at Grubers store and Richie would go by with the 435 I would get all flustered cause I knew it was Him"
Dad passed away at 44 but my brother still has that 435.... Mom is 78 and and lives in town but still loves the tractors