Standard of exported US aircraft

I am hoping for some concrete views or information regarding the standard of aircraft exported by the US.On several occasions over the years I have read that the radar systems on exported US aircraft were not up to the same standard as those provided for US forces in case US forces had to fight against planes sourced from their own country, is there any truth in this? I had also read [somewhere] that the US congress had passed rules regarding the standard of resolution on radar fitted to exported planes. This is not about source codes effecting which ordinance the plane can carry. I have taken a bit of a beating on a home forum [Oz] T5C because I cant quote any sources for my views regarding exported US fighters. Maybe they are right , does anyone have any concrete info on this subject please.