Two remote fan cooled stacked coolers and I needed to have them on all the time with the Heat exchanger removed! Before it never got above 160 without the fans on!
I forgot to mention that I also removed the front factory cooler at the same time! I have since put it back on also!
On my 2nd gen im running just the stock oem front air cooler and I haven't had heat issue yet. I haven't towed but I have 3.55 gears and 37" tires at the moment. I run around locked most of the time so I'm sure that helps. I've seen about 155-160° idling through the pasture. Also I did a couple boosted launches back to back and it brought the temp up quick from like 100 to 160. But it's also been very mild outside temps right now too.
I do have a 31 row ford trans cooler off a 6.0 that I am going to install soon.
Mine failed and that's why I removed it (not CR, 12V - 97). It didn't mix coolant and trans fluid, but it started leaking trans fluid around where the bung is welded. It's got rust there and I have thought about trying to fix it, but I think I'd rather do something else.
My trans lines are Aeroquip soft lines so I can put it anywhere. I might find another one to toss on. I had to butcher my bracket though since two of the mounting bolts stripped... Just a ****ty area on the truck, and I like the extra room for exhaust now.