Marcus has an excellent write-up on 67-up top loaders and paint marks.
But the finishes on the cast iron appear to run from sandblasted to charcoal gray.
The former is on DNO's website for back up lights.
The pic in the attachment is from Jeff's write-up on various paint marks and the main case looks painted as there are no machine highlights around the shift holes.
Many of Marcus' pictures show the same color.
I glass ball bead blasted my input shaft retainer and just gave it light WD coating.
I also blasted my extension housing but treated it same as my steering box -- light phosphate with steel wood into WD-40.
The extension housing I believe is the right color.
Is the main case this color too or charcoal? I did notice the inside of the main case is very dark but this may from years of running in 90wt.