The thing about the fuel pump vs pressure regulator is that some vehicles, even within the same model-generation, even with the otherwise same engine, have historically moved from a fuel pressure regulator on the fuel rail atop the engine, to one mounted on the fuel sender (which is an assembly of pump, strainer, fuel level sensor/float, and in some cases the pressure regulator) in the tank.
If the regulator is in the tank it's not a sure diagnosis without pulling the sender out, unless the pump does not spin which can be determined audibly or from current draw and/or frequency on power rails which if you have another of the same pump can also infer RPM. If the regulator isn't in the tank then you can get a (disabled regulator) pressure reading to see if the pump is suitably above the required pressure range.
Something rattling could easily have been a sender with a built in regulator and the regulator valve itself failed. That is a pretty common fault, but often the mechanic would recommend replacing the entire assembly including a new pump, at least if getting to it requires dropping the tank instead of going in through an access panel. If there is an access panel or if the emphasis is on cheapest repair possible, maybe then just replace the minimum.
You could tell which type it is by looking up the parts per vehicle on a site like Rock Auto. Sender with built in regulator usually has a big block of plastic on it. Separate regulator will be a metal chamber with at least two hose or pipe attachments. Well it doesn't have to be metal but on most old domestics I've seen it is.