You’re welcome. I don’t know if 62 in your DRF number has anything to do with model year of the engine or not. I’ve got a few DRF examples in my photo collection and the numbers don’t usually relate to the model year of the machine. However, one Big Twin case is stamped 55DRF9+++ so it may be a 1955 model but of course someone could have stamped 55 on the boss after the other seven characters were done.
You said your DRF number is located to the right of the boss but that the boss does not show any sign of being ground off or filed. That seems unusual as my examples have the DRF number on the boss. Can you post a photo of the number boss please.
I mentioned in my first post that DRF was said to stand for Department Registry File and I found the notes I made about that from another forum in 2007. But DRF in that instance was said to be on the frame not the engine. Apparently in the 1950s–60s when Harley only had an engine number the LAPD had the state issue them a Department Registry File number on the frame. This way when a bike came in for an engine rebuild they would take a rebuilt engine off the bench, swap it into the chassis and have it out the door the same day.
I also found the other DRF mention that I couldn’t recall earlier and that one came from a different forum again but it too applied to the frame not the engine. According to that source, DRF stood for Department Registered Frame and California was said to have had a program where the frame was stamped DRF along with a number so that procedure allowed the owner to change motors in a similar fashion to the abovementioned practice used by the LAPD.
If yours is registered as a 64 then there should be some reason for that so you could be right in thinking it was first sold as a 1964 model. However, if it’s really a 62 block then you won’t have a GE engine because the GE as an electric start machine wasn’t introduced until the 1964 model year. (There were some GEs in the 1930s but they weren’t electric start models and they weren’t stamped GE. The paperwork said GE but the engines were stamped as R-series or W-series, depending on year.)
Also, there were changes to the left case casting for 1964 models although the casting number remained the same: 112-392. Let us know what you find when you’ve checked the belly numbers.
Regarding the parking brake, I know little about them. On page 121 Palmer says the brake for 1951–72 S-Cs locks the front instead of the rear etc. I assume you read that page?