Fuel filler neck gasket

[Shoooter]

My cuda was lip up. I think it would seal better with the flat down as well. Here is a untouched trunk of a 70 challenger as far as I know. It's hard to see but it looks lip up as well

[Tony 73]

Fantastic help guys , much appreciated.

Cheers Darren, did wonder why my friends Cuda had so much painted in the trunk.