I have 2 zebrawood grizzlies. The serial #s are 5P4246 and 5P4484 which I believe makes them both 1965's ? Thing is they seem different.The lower # has what seems to be a smaller and slightly different grip and silver coin. The higher serial# has a stabilizer insert and a more rounded grip and brass coin.I had read that they changed the grips some after 1965. Did they change the Grizzly in the middle of that year?