Sixty4x4

JJay - forgot to mention that the Chev LS and tranny conversion most likely moves the TCase back so you will have to shorten the rear and lengthen the front DS's. Mine actually moved rear by about 2-1/2" so it actually made the front DS better being a bit longer. Not sure if the 4L60e is different length than my 8L90 most likely is. And I would go with 4.88 ratio diffs if you are using big tires (35"-37") Careful driving as mine will burn rubber on dry pavement now if you punch it too quick. Wet road - spins on 1-2, 2-3 & 3-4 shifts. Can't imagine what a 6.2 does.

Wiredup27

Doing a 5.3 swap on a 2012 jk, have some thoughts in my head and wanted to see what you guys thought. Looking at using a holley terminator x to run the engine, it can also run the efan and ac. I’ll either get a manual shift tcase and figure out how to make the jeep 4x4 shifter work or add some buttons for an electric tcase. Not too worried about the gauges, gonna get a screen for the holley. I’m thinking that if i clean up the jeep harness and leave it in Ill still be able to use all of the factory equipment (lights, radio, window controls,etc) anyone know if this is possible?

drapperson

Definitely possible, but I've heard it can be tricky with the A/C controls.

Back around 2018 on facebook, Wheats Offroad posted a similar setup to what you're doing, maybe using a Duromax instead of LS. It kept the Jeep cluster in place and had a holley screen with a coverplate mounted over top of the Jeep cluster. I think and it might have been someone else's work, but regardless, I didn't get any response when i messaged them. Hopefully you have better luck.

All of the body/accessories (lights, radio, windows, a/c controls, multifunction switch, wipers, power locks, power mirrors, cruise control, etc.) run through, or are controlled by, the instrument cluster. Modern instrument clusters like these are black magic to lots of companies. So lots of conversion kits (including some or all high-dollar ones) are actually additional systems, but utilize stock guages/display through proprietary coding/wiring schemes (where the high costs come from). In other words, you maintain your Jeep computer system, then add in another one for engine/transmission/transfer case, which splices into the Jeep cluster/harness/ecu/tpm somewhere along the way.

If you want the factory controls (multifunction switch, steering wheel, a/c knobs, etc.) and you're good with electronics, one option is to test/map the connection pins on the back of your instrument cluster and TPM, then power them from relays (for example, from the ignition position). My interior lights only turn on when I manually push them. After testing the pins to find the issue, I talked to at least 5 companies that "fix any instrument cluster" yet told me they won't touch mine and that I need factor replacement). I tried spicing in a low-voltage relay to trip based on an tiny voltage change (something like 0.2 v) from the door position switches, but I couldn't find a suitable low-voltage relay to do what I needed.

Another route you might cringe at is to use a mopar/hemi. As I understand, you're left with only one system: you keep your factory harness and cluster/gauges, and replace your ecu with the donor's (after flashing it). I didn't explore this option very far because I was stubborn about an LS, but I'm almost certain that swaping in any modern mopar v8, like from a charger or grand cherokee, is much simpler than an LS, especially if you still want your Jeep's interior controls to work. Junker Hemi's are generally more expensive, but you get a much simpler result that's much easier to troubleshoot.

Please keep us updated on what you find out and decide on. I still have a giant pile of parts waiting for some good news.

Sixty4x4

Wiredup - Drapperson has a good recommendation with going for Hemi conversion insead of LS. Not a lot of companies support LS conversions anymore. Why I went with LT plus the better transmission.
The Hemi uses the Jeep ECU (but reconfiguring required) and requires only a few wiring mods to original harnesses. Are you manual transmission cause if not I understand the Hemi bolts up to the 5 spd auto. You will need to do some custom programming for the tranny due to higher clutch pressures required on the auto behind a V8.