If you're talking about the black grill (cowl vent cover) that the washer fluid squirts out of, yes it comes off and very easily. Texas Mustang parts has them for $69.95.
As for stupid things, I'll tell you what I did. I basically rebuilt my car. New engine, fuel pump, transmission, exhaust, etc. Did it all at once. There are a lot of things to check. I missed one. My fuel line was running right by the exhaust back by the fuel tank. It actually fell on the exhaust and got a hole burned through it.
My maiden voyage had to be to the smog station to have it checked so I could renew my tags. On the freeway, I noticed I was dragging something. I pulled over and it turned out that one of my fuel tank straps was hanging along with the fuel tank. I also noticed the dripping fuel. I figured it was caused by the tank dragging. Anyway, I tied it up the best I could and drove it the the closest service station I could find. They also found the hole in my fuel line and fixed that, too. I think it took a year for the drip marks out of my driveway to go away.
Anyway, the excitement of getting something new can sometimes distract us. The part that sucks is how much it can cost sometimes.
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351W 89 Mustang GT Convertible