Have an old home with cistern tank/ pump. There is a part (sealed plastic bowl with float ball inside) attached to pump via 1/4 chase nipple with hose coming from bottom running into 3/8 inlet into pump.
The bowl is cracked and need to replace unit. Is it a pressure or water level gauge? Can pump run without?
What is it called and where can I find. Have been all over internet.. can't even find picture of...

Assuming that the pump pumps water from the cistern to your house. Is that correct? If that's the case, then assuming again that the pump pumps into a pressure tank, and there is a pressure switch near the tank that controls the pump. Correct?

If correct on both counts, then I can only guess that you are dealing with a float valve which is supposed to shut the pump down if water in the cistern falls too low. Hard to say. If that is the case, then you could go without it. From your description, however, you did not mention any electrical connection from the float to the pump, so I'm not sure how it would cut the pump off. Can you post a pic of this thing?