grounds are the connection to the body which flows back to the battery negative. For DC (Direct Current) electric items to work you need 2 things. Positive going in and ground coming back. Take away either and it doesn't work. Loose/corroded grounds inside the bulbs and at the body connections...
2003 TJ D35 rear and D30 front low pinion. If I were you and it's being lifted, I would get an XJ front diff to swap in (high pinion is better driveshaft angle for lifting) Maybe find someone with a 4.0L TJ that wants those nice gears and swap diffs with some $ in your pocket you can put towards...
For me, when I click on the email showing new posts, I get sent to the first post on the thread every time. I usually click the for sale one and then choose new posts link at the top left to check what I've missed and get the newest posts that way.