I just drug in a 1971 Dodge D100 Adventurer that appears to be
an original fc7 from the factory. Did they actually paint these trucks
fc7 in 1971? I have never seen one before. TIA

Apparently so: https://board.moparts.org/ubbthreads/ubbthreads.php/topics/3259204/1/1971-dodge-the-dude-pickup.html

This one does not appear to be a Dude.

FC7 for a 71 dodge truck is Dark Green.

Plum Crazy is C7

https://paintref.com/cgi-bin/colorcodedisplay.cgi?model=Dodge&year=1971&con=yo

There is no paint code on the truck. I guess I'm just used to car fender tags.

Sometimes there is a small paint code tag riveted to firewall above master cylinder area. You might look there.

When did they put the info tag on the inside of the glovebox door?

That's for cars, click on truck to see the available truck colors.

https://paintref.com/cgi-bin/colorc...odge&model=Dodge%20Truck&rows=50

There are several 70-71 Plum Crazy trucks known that were not Dudes. I do not believe it was even a factory available color on trucks, but a special order. The tag that appears on the firewall of some trucks is not a paint code, but a number that corresponds to a number on the build sheet and there should also be a tag on the front of the bed.

Color code FC7 breaks down like this:

Model year offered F (1970)
Plum Crazy/ In Violet C7

Therefore, FC7, if you include model year designator.