I was given this 2006 Rubicon from a family member about five years and I neglected most maintenance work for a majority of that time unless something went wrong and only got routine oil changes. I’ve just recently started trying to perform routine maintenance on my own - I’ve only done brakes, gotten new tires, and did a rear diff fluid swap. Yesterday I crawled underneath and noticed oil on the bottom side of the transmission and oil pan, none on the ground though. It’s causing a lot of gunky dirt buildup and I’m curious if it’s a rear main seal issue or perhaps coming from the top of the engine based on the last photo? Photos 3&4 are of the sides of the transmission. Any steps, tips or videos you recommend to help me figure out the cause?