Combination of Lucas trans fix, and synthetic blend.
I had some rattling when I first got it, the reasoning for the Lucas... however after draining the fluid, it looked as though it'd been quite sometime since it had been changed. It was BLACK and had no viscosity to it, real water like.
It did quiet down the trans and it shifted better. 6k miles later I replaced the clutch, and did a fluid change again with the same. I am now coming up on a year and 20k miles since clutch change, and thinking it's about time to swap fluids again since I do a lot of hard city stop and go driving.
I think next swap will be straight synthetic, since it only takes a little bit to fill the trans.