You've got an '04, so you need to be careful about what fluid you use. Your model calls for WS ATF which is NOT compatible with the other types of ATF (T-IV, Dexron etc). Your procedure for changing fluid is also slightly more of a pita since you don't have a dipstick.
I know I sound like a broken record but I don't think you can tell whether the driveshaft is "properly" lubricated by visual inspection - b/f spending the time on the ATF change, 15 minute lube of the driveshaft is probably worth it.
I posted the procedure I used for a full fluid replacement for ws atf:
https://forum.ih8mud.com/100-series-cruisers/447398-ws-atf-flush-procedure.html?highlight=atf
I know there are other good/better posts with pics as well.
You may want to go for a simple drain and refill instead of dropping the pan and doing a full flush - but either way, pay careful attention to the procedure to check that the fluid level is correct (i.e. vehicle is level, temp check mode says your at correct temperature, and engine is running when you undo the drain plug, etc.).
As far as alternatives to WS ATF, I think there are some (
https://forum.ih8mud.com/100-series-cruisers/296238-ws-atf.html) but it might be worth sticking with toyota's WS ATF to be sure.
See Toyota's TSB TC008-07 for more info about WS ATF. Here's excerpted info:
World Standard (WS) Automatic Transmission Fluid (ATF) was introduced to reduce
maintenance costs and increase the mileage between scheduled maintenance checks.
Here are some important tips when working with ATF-WS in Lexus vehicles requiring
its use.
2004 – 2008 model year Lexus vehicles equipped with automatic transaxle
requiring ATF-WS.
100,000 Maintenance Interval — Inspection only; ATF-WS does NOT require any
flushing or changing during the life of the vehicle.
The use of Genuine Toyota ATF-WS is recommended.
The use of additives or aftermarket fluids that are considered compatible
or substitutes may result in shift concerns and damage to the internal
transmission components.
ATF-WS is NOT compatible with T-IV or Dexron ATF.
Containers storing Toyota ATF-WS should always be sealed — If exposed to the
atmosphere, ATF-WS may absorb moisture and potentially cause shift concerns if
used in operation.
One time use only.
When performing repairs on ATF-WS equipped transaxles, it is important to use
only new, clean ATF–WS when refilling the ATM.
ATF-WS equipped ATMs may use the overflow type procedure — Any fluid
drained from the overflow plug should be discarded following proper local
regulations and never reused. Failure to do so could result in shift concerns and
damage to the internal transmission components.
From TSB at original release of WS-ATF (TC009-03), there's more warnings about why not to use non WS ATF:
The following symptoms will occur if non–WS ATF is put into a WS compatible
automatic transmission:
Non–WS ATF has a higher viscosity. Because of this, response to changes in
fluid pressure decreases, lengthening shift time, causing shift flare.
When the fluid temperature is low, (approximately –40°F (–40°C), air can enter the
oil pump causing cavitation resulting in low fluid pressure.
Fuel consumption increases.
The following symptoms will occur if ATF WS is put into a non–WS compatible
automatic transmission:
ATF WS has a lower viscosity than other ATFs. Because of this, response to
changes in fluid pressure increases, shortening shift time, causing shift shock.
If WS is filled into a non–WS automatic transmission, the fluid could leak out under
high temperatures (approximately 284°F (140°C).
Vehicles that use ATF WS can be identified by:
A. ATF dipstick is no longer installed.
B. “WS” stamped on the refill plug.