Looking for more information on my Panasonic sl-1000 sp-10

i recently purchased a Panasonic sl-1000,  epa-99, sp-10 at a garage sale but I can't find much info on the internet about it. I bought it from original owner, who bought it overseas back in 1969. I know its a universal model, because of the adjustable voltage. The name plate on it says Panasonic. Not National panasonic or Technics by Panasonic. It also came with all three original owners manuals. All the 1969 sl-1000 that I've found on the internet says National Panasonic. The serial number on it says 600128. What I was told is, it was made in Dec of 1968 and it was the 6th one made but wasn't for sure if it was for only that or the whole production for that year. Any help would be greatly appreciated.  thanks