I don't buy the 100% compatibility with any color garbage spewed by the marketing team of these antifreeze companies.
Your truck is not going to overheat, won't blow up driving down the road, in fact, you will likely notice zero difference between before and after.
However, you're introducing a new coolant chemistry into the system that wasn't intended to be in there. I'm sure Prestone has tested their coolant with all the different types out there to determine that nothing bad is going to happen, but it's still an unknown exactly how it will perform or what service life to expect from the mixture.
It stands to reason that 100% of the recommended coolant would perform acceptably LONGER than an mixture of unknowns.
I would maybe change it out a little sooner, but I wouldn't go out of my way to change it immediately unless you used a ton of the stuff.
FWIW, the coolant used in Chrysler vehicles of that era was G05, which is an extended-life organic acid based chemistry that is low in silicates (which was a component of the old green chemistry). If you buy the Zerex brand, I believe it's gold in color, but you can get the orange (I think it looks more like pink) colored G05 at your Chrysler dealer.