I have 2004 V6 SR5.
The part number for my vehicle for the accumulator is 47950-30010, the seller on ebay goes by triplecreations
The part number for my vehicle for the piston kit is 04493-60350, the seller on ebay goes by Partslane.
You'll want to verify for your vehicle for these parts...
Having just have the same issue as you described, up to the same spot as leaking I can hopefully offer some advise.
On the nut, the 4th nut is hard to get to, the top left nut. I had to use a swivel connector with a rachet. that was the easiest way to get it out.
I will be replacing the...
I've been using Redline D4 ATF since new.
I replace the fluids with D4 ATF at 10k and immediately notice the smoothing shifting. I have Redline products in my BMWs and you can tell the improvements in shifting expecially during winter cold months.
I'm a firm believer in Redline products now...