[John Brown]

Black caps (D308 and D308R) were used on most all cars, the brown caps (D309 and D309R along with some other long numbered caps that don't have a shorter Delco number) were used mostly on transistor ignition distributors, although they were standard on a lot of bigger trucks too. Also, the D309 when it started back in the 50's, was just a standard black cap with copper terminals. I don't know when they changed the composition of the plastic that changed the color to brown. I only know that I have bought many nos D309 caps in still sealed zip string boxes and most in the early black and orange boxes were black and most in the later orange and white boxes were brown (no dates on the cap or the boxes of course). I have bought several nos distributors dated 1965 and later that came with brown caps with copper terminals. What makes it even harder to pin down, sometime later Delco went back to manufacturing the D309R out of black material again. If anyone has a question about part numbers for cap or rotors or such, just give me the distributor number and I'll gladly look it up for you.