I have to go pull the (new)(er) transmission later today (story eventually) but have a little time to update things.
In January I started researching engine options. I had settled on a GM V8, but there are lots of block materials, displacements, compression ratios, displacement on demand or not, transmission options, etc.
Having rolled a truck once, weight was on my mind. I was really leaning toward the 80-lb weight savings of an aluminum block, even if it was more expensive. Initially I liked the L33 that has been done a couple times on this board. However they are hard to find, and only come mated to a 4-spd auto. As I watched acceleration videos of even the 6.0 v8 swaps I noticed something I never liked about my stock 1FZ and A442F... a HUGE jump between each of the gear ratios. So I started looking at the 6-spd auto from GM.
The 6L80 (they dropped the E for this model) is, by all accounts, a great transmission. Very good ratio spread, starting at 4.03:1, and has two overdrives of 0.85 and 0.67:1. Internally it is pretty simple, guys are making big power on stock setups. The computer is built into the pan which simplifies wiring, and the tuning options for how the thing acts are staggering.
But.. you can only get a 6L80 on "genIV" v8s or newer. This means ~2007 or up.
I spoke with @RockJock82 (THANKS, by the way) about engine options and he ultimately said "just get an L92". Not really knowing what this was I started reading.
L92= All-aluminum 6.2L V8, no active fuel management (displacement on demand.. unreliable parts), but does have VVT.. "medium" compression so premium fuel not strictly needed, has truck accessories which are much easier to fit and a mechanical fan is easy.. oh, and 400hp 420lb/ft.
Basically it's a lower compression LS3 with truck accessories. If I could put together a theoretical wish-list of what I'd want out of an engine (other than diesel), this was it. I had to have one.
I found a wrecked 2008 escalade at a junkyard in Houston, and had them pull the engine/transmission/accessories/harness/pedal/BCM/ECM/etc, and I went down there and grabbed it. 120k miles, probably not the best maintained, but these L92s aren't easy to find and I will deal with any reliability issues with a likely rebuild eventually.
This is where a lot of my work documentation started to move to the v8 swap thread sticky in this forum section.. but I'll try and copy everything over here eventually.