I'm looking at some 06 GS430. I saw they didn't make one in 2007 and made a GS460 in 08. Did the GS350 replace the GS430 when this happened?

 

they made a GS450 in 07.

 

They made a 430 in 2007 but they are extremely rare because the 450h came out in the same year and seemingly overshadowed its V8 sibling.

2006 they made 300 and 430
2007 they made 350, 430, 450h
2008-2010 they made 350, 460, 450h

There was also a mid-cycle refresh in 2008 with minor interior and exterior tweaks.

For more info check out the FAQ Sticky....

 

Is the 08 gs350 comparable to the 06 gs430? I know the 08 gs350 has a v6, but as far as interior room, actual car length, etc. go, are they fairly similar?

 

In a nutshell, all 3GS (2006 and newer) are the same vehicle except for the engines. 2008 had some very minor updates (grill, mirrors, guage faces) but as far as dimensions interior and exterior - they are identical.

As you research a bit more, you'll realize other details like upgraded brakes from 06 GS300 to 07 GS350 and so on.