[John Brown]

Cap inside the box is most likely brown judging by the color of the box and the black lids on it. The D309 number was used from 1959 thru 64 on heavy duty Chevrolet trucks, 1961 thru 68 IHC that had a Delco distributor, 1959-60 REO, 1960-62 White, and 1967 and 68 Corvette L-88 with TI ignition, which used a brown cap, per the NCRS judging manual.

Black caps sometimes came in boxes labeled D309, depending on the year they were manufactured.

1969 Corvette L-88 also used a brown cap, but it was a D309 R, which has the letter R raised up on top of the cap. On ocassion, I have punched a small hole near the metal lid and used an inspection light to verify color of the cap inside, but that is totally up to you.