MoTech , I have a 2013 JKUR Auto , I am interested in putting the 6.2 LS in mine , since i have the W5A580 Auto , would I have to still change my tanny or could the LS be adapted to it ?
The A580 is a step up from the 545RFE and a big step up from the 42RFE; however, the A580 is a step down from the 6l80.
The 6l80 is a modern clutch to clutch low friction transmission. It has a 4:1 low 1st gear vs the 42RFE's 3:1. The 6l80 has two true overdrives ending in. 667.
The 6l80 can handle over 800 ft lbs of torque and is readily available. The 6l80 is networked (can) for optimal functionality of cruise control, rpm match shifting, tap shift and more. The 6l80 is adaptive (learns) how you drive. The 6l80 is easily programmed and the same transmission can be programed to push a Cadillac or run the ¼ mile.
The 6l80 is somewhat the magic transmission. Any more gears (7-9) are unnecessary IMHO with a large vvt petrol engine, which has a wide torque band. Diesels and small engines can benefit from more gears.
GM has the software figured out which helps and if you don't like it tuning is easy.
I know (and help) guys trying to make the 6l80 stand alone so it can be used in other apps such as the SBC, BBC and Hemi. It's tough though because the 6l80 TCM is married to the Gen IV ECM. IAT changes 1 degree and so does shifting.
So my long winded answer is no with an LS you can't run the A580, but you will be better off for it.
BTW we have customers go with an LS just to get the 6l80. And when I follow up with a customer after a swap they usually comment how awesome the transmission is.