Where Does One Find This "whatchamacallit?"

I got my new water pump this morning and need to find this piece shown in between the two pumps. I do not know the proper name, so chasing one down online is slow. If you can share a name and/or a source for these, I will drink a toast in your name later. Also, if you look closely, the openings for these are different. The newer pump has a smaller opening. I don't see a major problem with that, is there? I just want to find the correct fitting. And correct me if I am wrong, but this opening draws water in from the heater? Thanks all, and have a wonderful weekend!

 

Heater elbow?
Yes draws cooled water out of the heater and back to the motor.

 

Addendum to original post: I have found some that are made of aluminum... will there be corrosive issues there?

 

The original was plated steel. I would not use aluminum due to possible electrolysis.

https://www.amazon.com/ACDelco-15-31770-Professional-Heater-Fitting/dp/B00555FA7I/ref=pd_lpo_3

 

I was able to flush using the heater hose that attaches to the rear of the head and I did flush before removing the water pump. Now that the pump is off, I want to flush again several times before and after I put the new water pump on. It was pretty crusty where the impeller spins. And the back of the impeller had lots of crystallized flakes on it that chipped off easily. I'm thinking there will be lots to clean once new system is put in place. Is a chemical flush a good idea? Or will that dissolve too many parts that could cause harm? Here are views inside the head from the water pump side and the thremostat side.

 

A good Radiator Flush product does no harm........I's better than the flake that is in in there now.

 

I agree... I might put in an old radiator I am having boiled right now for the first month or so. But your idea of a screen is a good one. Maybe a long length of flexible hose with a bunched up window screen in it? I could pull that out periodically and shake it out. After several flushes, maybe put the new radiator in. Time to ponder more.