Page 13 of the original AA manual…
“Just as in trasnporting infantry, it would be illegal for tanks to move one land territory, before or after boarding and landing (even though tanks can normally move on land 2 adjacent territories, the boarding and the landing counts as a tank’s full move!).”
And just FYI: this is different from the Hasbro CD which allows a tank to move before boarding a tranny, but not afterwards (for example, if you have a tank in Yakut, you can drive through Manchruia to board a tranny in the Sea of Japan, then move 2 spaces, and offload that same tank to attack Pearl or Alaska (as an example). Just another Hasbro glitch…