Water pump issues.....

I bought an aluminum water pump for the 66 at Checker auto today. The thing was 23 bucks and I couldnt pass it up....anyways the pump differs from my current cast pump and will not fit. First difference, is that the impeller is not covered, and is open, 2nd the outlets have small "tongues" on the end. The pump has all the right bolt locations, and the inlet is on the passenger side. My current water pump has a C8 casting number....indicating a 68....from all the parts catalogs, the 65-70 pumps are the same. any help would be appreciated. Thanks guys

Mike

The impeller is popped out and not recessed like my stock cast pump. I returned the pump today.....They told me that they do not make a replacement pump in aluminum....Im off to buy a edelbrock pump

mike