bellhosing color

I'm doing a restomod on a 1969 Fastback. I'm wanting some of the motor parts to look stock but still have that new edge. I was wondering what the factory color was for the bellhousing. I have a 351W if that helps any. Thanks ahead of time for the info.
 
in some cases it was painted ford blue and in some cases it was left natural aluminum but probably with some blue overspray from where the blok was pinted with tranny mounted up. personally i would do it totally natural aluminum or at least painted with a natural alum. finish