A750F 5 Speed Automatic Transmission uses 11.5 quarts of Toyota ATF - WS fluid. Although claimed as a lifetime fluid many owners recommend changing the fluid. There are other fluid that are compatible with Toyota WS. http://www.amsoil.com/lookup/auto-and-light-truck/2005/lexus/gx470/4-7l-8-cyl-engine-code-2uz-fe-e/us-volume/
This is a detailed how to for the procedure to change the ATF fluid. https://forum.ih8mud.com/threads/ws-atf-flush-procedure.447398/
|Transmission Pan Gasket||35168-60010|
|Transmission Filter O-Ring||90301-31014|
|Drain/Fill Plug Gasket||35178-30010 (2 Required)|
Rear air bags (suspension)
The rear air bags will eventually fail. A coil conversion is the most common fix, as it's better for off-road purposes and also cheaper than replacing the OEM air bags.
Secondary Air Pump
2005+ only: Congratulations - you have 35hp more than your earlier brethren! Unfortunately, this comes with some emissions complexity, namely an air pump that requires intake manifold removal to repair or remove. This does not impact driveability at all, just cold-start emissions.
CD changers sometimes fail, though with a pre-07 you don't have MP3 capability anyway so you might as well throw it out and install a bluetooth/aux adapter instead. VAIS and GROM both make plug and play units.
Rear Interior Door Handle
The inside rear door handle breaks on basically everybody's GX. You can get a new one online from Lexus for about 20 bucks, or fashion/buy something else out of paracord, nylon webbing, etc. If you buy one from Lexus, use your VIN to look the part up so you get the right color.
2003-2005 Diff Support
The passenger side front differential support was reovised for 2006. If you have a 2003 to early 2005, you will want to install the updated front differential support from Lexus. Sme 2005 GX’s have the updated part from the factory. Failure to do so may result in the differential support catastrophically failing, which is a really bad day for anything close to the differential (i.e. your oil pan, and consequently your motor).
Toyota Part for ordering is#52380-60021: Support, Front Differential, NO.2 However the number stamped into the side of the part is 52391-60021.
8" Rear End
The factory 8” rear end is known to be weak. If you wheel enough, it’ll probably break. On the bright side, this gives you an excuse to re-gear and add lockers!