How to Wire Up Ultrasonic Transducer
See Kerry Wong's article

You'll need to create something like the following circuits




Personally I'd buy one of the pre-built modules that are much easier to use



As others have noted, using separate Arduinos for transmit and receive will make the project much more complex and less accurate.

I haven't tried any of the above and can't vouch for it.



Polarity is given in the datasheets. sometimes the +ve leg is longer.