US fighters are using SAAB equipment. Here is one example:
http://saab.com/air/electronic-warfare/countermeasure-dispenser-systems/bol-fa-18/
Other examples is the Excalibur GPS controlled round, which manufactured in the US under a license.
They can certainly be redesigned to use US equipment, but that is going to take time and money.
If the US stops engine deliveries and breaks the contract, the US will be sued through WTO
for several Billion dollars, and Gripen will be redesigned to use a European Engine and other stuff.
That is asking for a trade war with the European Union.
As for Brazil, this would be considered an insult, and it is not unlikely, they buy Russian, or even Chinese to get even with the US.
OR sue the US, and ask for them to pay for Rafales,as compensation.
Since noone is even discussing this, I suggest you stop fantasizing.