Both the transmission and the power steering use Dexron II/III.
I would thoroughly clean and degrease the whole area, then run the truck for a week or so, so you could be more sure where any fresh leak came from. Then you can be sure what area to focus on. Check your power steering fluid level though.
There are a couple of techniques to change the steering fluid, but I draw as much fluid out of the reservoir as possible (with a turkey baster), replace with new Dexron fluid, run the vehicle and repeat several times over the course of a few days until it’s clean. It’s easy to do and might use up a litre in total. Timmy the toolman is an excellent source of info too.
When I first got my truck, there was a leak from one of the driveshaft seals on the front diff. I suppose the gear oil would get flung off the driveshaft and blown backwards. It used to drip from the steering rack- see photos. You may have already found the correct culprit but oil has a habit of spreading and appearing to come from something else. Just saying - be sure you are chasing the right thing.