Today I went to the DoR at the Truman Building in Jefferson City, to transfer the title and register my YOM plates for 'Ole Blue', my '67 C-20. As anticipated, I didn't have any problems with the '67 plates, since it has six numerals.
While there, I had them check some plates I bought at the Sedalia swap meet this past Friday. They're for my '72 and '76 VWs, which will come up for renewal next year; I plan on switching them to YOM plates. Both sets of plates came back good. I was uncertain about them, since they have a different letter/number pattern (LNL-NNN) from what I've seen before. Once again, they referred to the secret green sheet of paper when checking the plates.
I have compiled a list of known good letter/number patterns, where L=letter and N=number:
NN-NNN
NNN-NNN
LLN-LNL
NLL-LNN
LNL-NNN
Just a reminder: For the love of God, do not buy any LNN-NNN plates! These are very common online, and are NOT able to be registered with the DoR.
If anyone gains reliable information of another acceptable pattern, PM me, and I'll update this post.
-Kevin