I've recently replaced my break light LED because they started to die one by one, based on other RX I've seen on the road it's a very common issue.
Driver side: 81563-48060
Passenger side: 81553-48060
The steps are pretty straight forward, my photos are from the passenger side job, the driver side is the mirrored identical. It took me about 40 min for each side but I took my time and was taking photos, its probably a 20 min job per side for most folks.

1) Pop the panel in the trunk and disconnect all 3 wires


2) Remove the 3 flange nuts from the inside (this is the view from the outside) and the entire housing can come off


3) Carefully remove the foam gasket


4) remove the 2 hex screws and the lamp assembly will become lose and you can wiggle it out. it takes some patience and angle to wiggle out the old one and insert the new one, take your time.


5) I plugged in the wire just to show the condition of the original lamp vs the new lamp



6) Reverse the process to put everything back together

 

Nice, didn't know you could just buy the plate and replace it with OEM parts. I would try to replace those burned out LED chips on the board and sell it off. The 330/350 assembly is a lot easier than the 400h one to repair. I have one apart now and I had to drill some holes in the assembly and remove the front lenses to get it off.

 

To OP, thanks for the write-up - I just did this last month on our 2004 RX330.
1) Small hands help
2) Put a cloth in the cavity, just in case you drop one of the nuts
3) The LED disc came out pretty easy, but patience is in order when re-installing into the housing
4) Bell Lexus has good pricing on the LED disc.

Otherwise, the repair is less than an hour and pretty straight-forward.

 

good pointers, I did lose a nut the first time when I worked on the driver side LoL, its forever sitting on the bottom of the cavity, RIP