it's supposed to be a direct fit but from the reviews I've read there's many fitment issues.

There is also an aluminum expansion tank made by Morosso that looks great, but I haven't found any reviews at all

:bustingup:bustingup:bustingup

/|\ Riiiight!

I think there might be something to the lower pressure cap, both our x the reservoir blew about 150,000 miles. Mine just ooked out the side I just noticed weak heat and low fluid didn't even find the leak for about a week of topping off. Wife's split wide open and blew out the coolant. She pulled over and called me. Fortunately happend ten minutes from home. I let the car cool off filled up with distilled water and drove 8 minutes to my friend’s house where I installed a local sourced dorman

That is one hard working 3.0 E53! I only wish mine can get to 2/3 of your awesome number!