Does anyone know what this is???

[Charger Aficionado]

I ASSume it's a drain tube, but I've had other '70s and they never had it...  My buddy Tolley is close to here said his '70 doesn't have one, and he's never seen it either...

[Shakey]

Was the car an old stock car by any chance?

Fuel filler tube for a road racer.   

[gtx6970]

Vapor recovery tube for either California emissions car (1970 and older )
Or All emissions 1971 and later

[41husk]

Huh! you never know what you might find on these cars?

[Brock Samson]

never seen one before,..
it goes from where to where?.. 

[MichaelRW]

It's the filler for the moonshine. 

[Just 6T9 CHGR]

Vapor recovery tube for either California emissions car (1970 and older )
Or All emissions 1971 and later

Bill is correct (as usual)

That goes to the gastank for vapor recovery on Cali. cars

[Chris G.]

And just to add, you will have "N95" on your tag to signify it was indeed a Cali car. I have been asked several times what that tube was. Most guys think it was some sort of second fuel filler.

[resq302]

Its a flux capacitor!   

[Rolling_Thunder]

Vapor recovery tube for either California emissions car (1970 and older )
Or All emissions 1971 and later

Bill is correct (as usual)

That goes to the gastank for vapor recovery on Cali. cars

yep...     has 4 rubber hoses that go from the fuel tank to that pipe...