Lines were leaking like crazy, so I pulled the lines off and when I tried to disconnect one of the fittings that was leaking that went into the cooler, I bent the tube. So the cooler is broken now. No big deal as it was beat to hell. I just saw an 80ish K5 this morning parked on the street, so I looked and it didn't have one. It was stock all the way down to the rims. So I'm guessing you're right, it was an add on. Can I just remove the cooler adapter and screw in the filter into the block?