Question for the vehicle audio buffs out there.  Is the connector (plug) and
wiring for a stereo head unit (receiver/CD player, etc) standardized
between  different brands?  In other words, if I have a modern (last few
years) head unit made by Brand X will another head unit from Brand Y fit
without having to rewire the plug that connects everything to the back?
Just curious, question prompted by a couple of questions I've received.