Thanks! I was hoping there would be more pics in this thread. I did not know about the grip length until just recently. It is not mentioned in the SCSW IV book that I have found.Here's a sample, no. 73,313. I've not lettered it but speculate it was shipped 1949. Interesting you bring up the "long" magna stocks. I purchased a pair of elk stags from a forum member intending to install on this HD but they were a little short (1/16" +/-) for the frame. They fit perfectly on a 1954 Highway Patrolman so your suggestion that the frame dimension changed to coincide with the change to short action makes sense.
Below is a pic of a damaged set I bought when it was mis-identified on ebay. Installed on a Model 28, it shows the stocks extending past the grip frame by about 1~1.5 mm:
And a thread where I am asking for help identifying what they are, with some good information from more knowledgeable forum members:
Damaged Diamond Magnas, Repair/Restore...?