I was in the same position as you last year when my original engine blew up. I wanted to retain the 3 OTT, or at least a manual trans. After some deliberation I ended up ditching the 3 speed and going with a junkyard NV3500. It was a fairly simple union between the trans and my 5.3 LS. I didn't do anything internal to the trans. Maybe I got lucky, but it drives and shifts great. Just thought I'd put that out there in case the 3 OTT option doesn't work for you. As for the electronics, these things are fairly simple when setup as stand alone and also quite reliable. It is definitely nice to just jump in and go in any conditions, with decent fuel mileage as an added bonus!
