I don't truly know what's in the power steering system, but the transmission has 2000 miles on the fluid and it's *bright* red and the power steering might have 180000 miles on it and it's not.
I've started looking casually at replacement transmission coolers. Since I'm not trying to solve a problem, I just want to basically replicate the stock cooler. I'm leaning towards Setrab as I've used many of their oil coolers in the past with great results. They're a bit pricey, but they make a quality part. Their SLM range is a long, narrow cooler with formal end tanks and edge-mounted bungs which would would fit great right under the bumper... The two I'm looking at are
53-10744-01 which is 12.60" long, 4.06" tall and sheds 14,000-15,000 BTU/hr with a 0.53 psi pressure drop
53-10747-01 which is 19.29" long, 4.06" tall and sheds 22,000-24,000 BTU/hr with a 0.76 psi pressure drop
The opening in the bumper is 22" wide and just under 5" tall so either of these would fit fine. I think the smaller cooler does the job handily... I don't think a small vehicle like the Jeep really needs the larger cooler.