Which generation?
 

Is there a sticky that explains which RX models are in which generation?

It is right there in the descriptions under each of the forum titles:

https://www.clublexus.com/forums/rx-models-9/

1999-2003 rx300 (gen 1)

2004-2006 rx330 (gen 2)
2007-2009 rx350 (gen 2)

2010+ rx350 (gen 3)

Welcome to Club Lexus, tbm5690.

Please keep in mind that these are the models and years the vehicles were sold in NA. There are also RX300 2nd Generation vehicles and possibly even an RX270 in some markets. Same body as the US and Canada, however, different sized engine. A 2004 RX300, as an example, used the 3.0L engine from the 1st Generation RX.

Also, there were 2nd Generation bodies sold in places such as Australia as a 2003 model year.