General questions on 06 GT and 06 GXP

My 99 GTP has 184k and the motor still runs very well. But it does have some accessory maintenance issues (like the A/C) that may take some time to resolve. I'm considering buying a "backup" vehicle. Two currently under consideration are a 2006 Grand Prix GT and 2006 Grand Prix GXP. (I also liked an 04 Monte Carlo SS but my wife is still laughing about the Dale Earnhardt head rests. :rofl:)

The GT has the Series III 3.8L S/C V6. Is this engine as reliable the Series II? Is it an improvement over the Series II? Are there any chronic issues or anything that bears close inspection?

I like what I've read about the GXP performance and the features. I became alarmed when I read that the engine is mounted from the bottom which complicates repairs...do you agree or disagree with that assessment? How tight is the engine compartment with that V8 in it? Is it more difficult to work on than the Series II V6 in a Grand Prix? Also, should I be concerned about the aluminum block in the V8? Are there any other GM cars with that FWD V8 so I know parts will be available at reasonable prices?

I appreciate any feedback.

The LS4 comes in 2006–2009 Chevrolet Impala SS, 2006–2007 Chevrolet Monte Carlo SS,2005–2008 Pontiac Grand Prix GXP, 2008–2009 Buick LaCrosse Super

As for the Series III SC engine I have an 07 GT. I just hit 150,000 miles and my car still runs great. If you are into modding and tuning you will find the 06's and 07's more difficult to tune. A lot of guys put an 04 or 05 ECU into their 06 or 07, but the gas gauge reads backwards.