How do you check the transmission oil in a 2006 GX 470?

I believe the hoses have tension style hose clamps at the cooler end of the transmission hoses, I would try replacing them with the screw tighten type used and sold aftermarket. There is a refill plug on the passenger side rear of the transmission and an "overfill plug" at the bottom of the transmission pan (middle passenger side), add World Fluid (genuine Toyota ATF)until it spills out the open overfill plug, start the engine run through all the gears. That will get approximately the right amount of fluid in the transmission but Lexus are adamant that a long list of instructions be followed to ensure the correct amount of fluid is in the transmission. The easiest instructions to follow are in Alldata under diagnosis and repair-transmission and drivetrain- automatic transmission- then look at A/T Fluid. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online