you
may need a crank spacer or a custom converter with the extra space added onto it. Apparently
some trucks came with a longer crankshaft and don't need the spacer, no idea how to tell though.Otherwise the crank won't reach a normal 4L80E converter snout to locate it. I used the spacer as I was converting my 4L80E and converter from a standard small block to an LS2.
http://www.gmcopo.com/engineswap.htm
You'll also need 5 trans to block bolts, metric for the LS2. The sixth bolt doesn't exist on the LS2, but five are fine. Sorry, don't remember the thread size.
You also need a trans controller to run the transmission.
Jody