Random House Historical Dictionary of American Slang, - The Only Historical Dictionary of Slang, Spanning Three Hundred Years of Slang Use in America, Volume I, A-G, J. E. Lighter, 1994, p. 483..

copacetic adj. [orig. unkn.; not, as sometimes claimed, fr. Heb, It, or Louisiana F} 1. fine, all right.

1919 in OEDS: "As to looks I'd call him, as ye night say, real copesetic." Mrs. Lukins expressed this opinion solemnly. It's las word stood for nothing more than an indefinite depth of neaming. 1930 Franklyn Knights of Cockpit 205: Gone loco, that's all – I had to sock him in the jaw, but he'll be copasthetic. 1934 in J. O'Hara Sel. Letter 100: " Copasetic" is a Halem and gangster corruption of an Italian word…In American it mean all right….

[ there are twelve more examples given and then the final one]

1991 J.R. Wilson Landing Zopnes 160: These sons of bitches ain't acting right. Something ain't copasetic here.

2. confidential.

1959 NYC grade-school students:Let's keep this copacetic. 1978 MacKillop & Cross Speaking of Words 147: Fewer still would remember the youth-oriented word from the 1940s and 1950s "copacetic" (confidential, between only us.)

Sincerely,

Gargoyle

Thanks for the hat-links. While in Maine – most folks wore their "crushers" (cheap LLBean felt hats) in the telescope style. I, on the other hand, wanted to be different….and used three dents. It is now clear that I styled it as a "packer"....curiously...because it was what I was most familiar with from the west where my first "pay-check-job" was as a burro-wrangler.