Excuse my lack of knowledge and a wall of text incoming
my 04 engines blew and long story short I’ve decided to ls swap. The route I’ve planned it get the marks 4wd kit to put a gen 4 ls (either l99 or ly6 or l96) and a 6l80e. I’ve seen that I could use either a 2wd or 4wd is that correct? I’ve called Howell and they can do the standalone harness and computer, they just need the gm computer and transmission controller, but on the phone I forgot to mention to them that I would have to swap the engine to a drive by cable. And then would that harness allow the things like my ac to work? I know I can maybe put my rover sensors in the ls. How would I get the fuel dialed in?

if some has done the gen 4 and 6l80 swap and they had a parts list I would greatly appreciate it.

also does anyone know of any shop that would do the work not for a insanely high price or take a long time? Since college is starting back up and I need the truck up and running. The shops I’ve called have given me quotes like 36k, the lowest I’ve got is 20k, both are out of my price range. I don’t need the best custom job just a engine and tranny that run with a working tach, check engine light, temps, and a ac, things like traction control and abs can be dealt with down the line.

 

Durham,
What vehicle do you have? D2? What is your budget? The engines you mention all appear to be in the $6K+ ballpark (this is engine and trans). The Mark's adapter kit is in the $2,200+ range and add shipping. This doesn't include any fluids, repairs or reseals to engine or trans, wiring modification/computer programming. A different engine option will net you a cheaper base starting point. I have heard of someone who is having his done by a shop approximating $10K, but not on an expedited time schedule. I think the $20K mark is a very reasonable price for the work that it would need.

All of that said, if you have some mechanical inclination and somewhere to work on this, you can do most of this yourself. The 6L80 only came with a 32 spline output shaft. That means the 2wd can be used once the pilot/threaded portion has been cut off. Why do you need/want to retain the cable actuated throttle? Realistically, you can use any harness you want. A lot of it comes down to how much integration you would like with the Land Rover side. You can do an aftermarket dash and just feed signals to that from the GM ECM and not worry about any of it. You can utilize some of LRs inputs to retain functionality and feed the necessary signals to the LR side from the GM side. Which method is most intriguing to you?
I am working on a parts list, but so much of the swap depends on how you want it finished out. For myself, I want it to appear as if Land Rover intended for the engine and trans to be there. I want everything to look factory and in its proper place. I'm happy to answer any specific questions you may have. Just know, this is likely not the cheapest option. A quality rebuilt 4.6 would probably be similar in price (or cheaper) and get done more quickly.