Re-read these:
www.impalassforum.com
sherlock9c1 knows his schidt.
www.impalassforum.com
After re-reading this post, remember that every LQ9 came attached to a 4L65E, which is a better-built 4L60E.

LS swap.. rebuild 4l60 or buy 4l80 ?
What direction should I go? I'm dropping in a 6.0 LQ4 LS V8, with around 400hp into my 94 caprice wagon. I'm looking for least amount of headaches and bullshit. Definitely want to keep driveshaft and linkage. Tell me where to spend my money smartly.

LS swap.. rebuild 4l60 or buy 4l80 ?
What direction should I go? I'm dropping in a 6.0 LQ4 LS V8, with around 400hp into my 94 caprice wagon. I'm looking for least amount of headaches and bullshit. Definitely want to keep driveshaft and linkage. Tell me where to spend my money smartly.