There's nothing wrong with '98 LS400's stock system, and it's good enough for me; my problem is I'd like to have navigation and some of those other goodies the newer models have. Can this stereo be replaced by a factory one out of a newer Lexus?

 

Anything is possible if you have the time,money and inclination but you would be better off with an after market system using a double DIN facia bracket and then fit what meets your requirements in there.

 

Only takes $$.

PD has a great write-up about an aux/MP3 type interface.
https://www.clublexus.com/forums/lex...em-stereo.html

For GPS, I simply purchased a portable GPS unit for $200.

 

I think more like $$$.

 

$$$$$$$ +luck and more money

 

Save yourself and take it out.
Those I come across lately with systems have significant hearing loss. At such a young age it is sad.