Some good info on stout GM AWD pieces/parts.
https://engineswapdepot.com/?p=4520
4L80E transmission, NP149 transfer case with viscous coupling, a Typhoon 3.73 front differential, and 3.73 12-bolt rear differential. The Chevelle can reach 0-62 mph (0-100 kph) in 2.75 seconds and 50-75 mph in 1.01 seconds.
Something tells me the Typhoon front diff is expensive... The NP149 transfer case looks like about 900 for a reman.
Here is the compatibility list for that transfer case:
27 spline input shaft
-Fits the following with a 4L60E AWD Transmission:
*2002-2006 Cadillac Escalade/ ESV/ EXTV8 6.0L
*2004-2006 Chevrolet Avalanche 1500
*2006 Chevrolet Suburban 1500
*2001-2007 GMC Sierra 1500 (includes Denali) V8 6.0L
*2001-2003 and 2005-2007 GMC Sierra 1500 HD
*2001-2006 GMC Yukon
*2001-2006 GMC Yukon XL 1500