273 New Water Pump

The last time I needed one I had the same issue with the heater hose requiring and adapter. I went to NAPA armed with the Gates number I had bought several years ago and they only crossed to the one with the larger opening. I went to Oreill and they ordered one and it came with the large hole. Carquest was also large and AutoZone was too. None had theat extra boss in your first picture though. I finally woound up buying the first one I looked at from NAPA and using an adapter. It has worked OK for a few years now.