The fittings are Aeroquip, they are big enough and flow and cooling is good. We've had a few different racks as well.
It's not just on one car, but on the main culprit we blew seals for a year, then fitted an underdrive pulley and didn't blow any for 6 months, then blew the engine and went back to a normal damped pulley and we started blowing seals again.
We're not just replacing seals by the way, we are replacing pumps.
I'm open to the idea of it being some other part of the system causing the failure, but with having no failures when using an underdrive pulley before, and a fast approaching new season. that's enough for me to purchase two damped underdrive pulleys at great cost