Going to reinstall the pump onto my 1998 GTX limited and purchased a pump seal but not sure how it goes on or if it is correct. It did not have a seal on it when I removed it. Part number I ordered is 293200051.
I don't have one in front of me but think of it this way... it has to seal on the face of the wear ring. So the rubber fits "over the the pump" and should cover the face/flat part of the wear ring which seals against the hull mount. I guess you are talking about the "big end" the larger internal section of the rubber... that fits over the pump. Hope this helps.