Delco Remy distributor cap question

[ZLP955]

Originally Posted by X66 714

According to the NCRS guidelines, if it shows the patent number, it's considered a replacement?...Joe

The extracts of the NCRS guidelines posted in that CRG thread only cover '67 to '69 model years.
Not sure when the caps started to have the patent number on them, but as it appears to be some time in the early 70's, it follows that one of those caps on a 60's car would be judged a replacement.

[Flying Undertaker]

Delco-Remy caps without the R would be for 1968 and earlier usage. In 1969 GM came out with the R (resistor) designation. Caps D 308R ( black caps with aluminum contacts ) and D 309R (brown caps with copper contacts) and rotors D 409R (black with E on tip of contact) and various spark plugs with R designation, such as R43 or R43N, etc. Patent pending R were used until the patent office OK'd the R designation as being different from earlier caps, rotors, and spark plugs without the R. Then the patent numbers were imprinted on the caps once approved with R usage.These parts were then used on earlier applications once the earlier parts ran out of stock.

[John Brown]

If you are still looking, here is a NOS D310 cap that has patent pending and the R on it.

https://www.ebay.com/itm/223454312472?

D310 looks just like a D308 but the towers that the plug wires go into are about 1/4 of an inch shorter. I doubt if anyone would be able to tell the difference once it was installed.