I removed the coolant flange to remove the tandem pump during my camshaft replacement. Glad I did, because the old seal was pretty crusty. At first, I was convinced this new seal was not going to work, because it seemed so loose in the groove. But, I went with it. I did cut off the tab, which, was probably not necessary. It would have squished down. Anyway, I installed it and just assumed it was ok. But, then I needed to remove the flange to install the turbo feed line and found that the seal had squished down and filled the groove perfectly. Interesting stuff that works well.