First picture, just to the left of the oil filter is the oil pressure sender. The temperature sender is up at the front of the head.
Center of second picture is the hydraulic pump. It is driven off a gear at the rear of the engine.
Looks like the model number is 21012A, which would be an early (1/65-3/68) 2000 with general purpose ag chassis, gas engine, trans driven PTO and a 4 speed transmission. The serial number is C156723, which would be a 1966 serial number. The production code looks to be 6L12B, which would mean that it rolled off the assembly line on November 12, 1966, during the day shift.
The transmission sump is just for the transmission oil. I don't think that the 4 speed had a dipstick. There should be a level check hole with a square headed pipe plug on the right side of the transmission case, just forward of where your right foot is when you're sitting on the tractor. The fill hole for the transmission should be on top of the trans, near the shift lever.
The hydraulic fluid for the 3 point hydraulics that is powered by the pump in your second picture is stored in the rear axle center housing. There should be another level check hole with a square headed pipe plug on the right side of the tractor near where your right heel is when you're sitting on the tractor. The fill hole for the rear end/hydraulics is on top of the rear axle center housing, under where your right butt cheek is when you're sitting on the tractor.
This post was edited by Sean in PA at 12:25:16 09/18/12.
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