Gear cover identification

[DarrinM]

While I’m waiting for my copy of “THE BOOK”, can someone enlighten me by telling me which year ranges these 2 gear covers are?
I have a 1926 engine and a 1918 engine and I’d like to put the proper cover on each engine.
Thank you all

[MMasa]

Darrin
While neither cover is correct for your 1918, the black cover is a mid 1922 - 1927 style and would be correct for your 1926.
The other cover is a mid 1928-1929 style.
Mark Masa

[DarrinM]

Darrin
While neither cover is correct for your 1918, the black cover is a mid 1922 - 1927 style and would be correct for your 1926.
The other cover is a mid 1928-1929 style.
Mark Masa

Thank you very much for that information