Any new DIY mechanic that changes fluid on a typical car automatic trans always freaks out over how dark the fluid is. That color change is due to normal clutch wear. Yes, there are clutch disks within the automatic.
There are a few clutch packs in the Gen 1 transmission but for the majority of drivers they should experience virtually NO wear, thus no darkening or discoloring of the fluid. But just because it looks good doesn't mean it's not worn out.
(I'll admit I'm talking out of my area of expertise here so feel free to flame me)
I suspect the only way to know if the pretty fluid is still OK at high mileage is to have an oil analysis.