How do you check hydraulic fluid on a ford 4000 tractor?

There is no dipstick or level plug on these tractors. The way to check it is to measure 18 centimeter from top of filler hole down to oil level.

There is level plug on 4000. It's right next to the parking brake lock. Square headed bolt. (For rear axel fluid level.) For the manual transmission the level plug is on the side of the transmission about where your right heal would go. ( square headed plug.) and if it's a selecto speed the plug is ahead of your big toe in front of the brake pedal arm.