I would at least put some paint on it, if it needs to stay in there.

 

good point i'm gonna work on that lol what color you thinking?

 

I would say black, but if you plan on detailing under the hood, go with what ever color you paint the truck. Either way would do. I'm still going to wait to see the final work.

 

the lightnings that body style were fleetside beds

 

I think the tin can looking thing, is a vacuum reservoir. On the newer body style f150s, it is inside the right fender well. If you look behind all the electrical on the firewall behind the battery, you'll see the vacuum lines going into the fender.

 

My guess was going to be a carbon cannister.
See if it is connected to the intake system and possibly to the fuel tank vent.

Basically, evaporating gas fumes go into it instead of out into the environment.

 

yea any guess is as good as mine, whatever it is im just gonna leave it and probably paint it black hah

 

Nice find. Looks like it will be a sweet project.