On that vintage of a tractor, it's most likely just an hydraulic screen and not actually a cartridge filter.
The screen will be located at the suction side of the pump. So you need to follow the suction line of the pump all the way to the transmission housing and then, you either have a cover on the opposite side that allows you to pull the screen out or you have to pull the suction hose/pipe out to pull the screen.
This is how it works for most tractors. It may not apply 100% to yours, but should be close enough.