"The customer got what he wanted," was Alf's motto in the 1960s and 70s, and the number of models was prolific. By the mid-80s, however, radical simplification was required to reduce production costs and stay in business. Accordingly, the 1987 catalog offered only three models. The Novus Ductor was the plainest of the three (the others being the MO and Scorpion Bonum). Superficially, the Novus Ductor differed little from the MO; the same tangs were brazed onto the same lug blanks. However, the MO head lugs typically had extra slashes on the sides, and spydery bits underneath; the ND lacked these. The ND was notably plainer on the bottom bracket shell, had shorter tangs on the fork crown, and short ones or none on the brake bridge; a few NDs are known with notably simpler head tube lugs as well.
Head & seat lugs slightly plainer
Plain bottom bracket shell.
Fotos above courtesy of Bob Johnson.
Above: Novus Ductor variations.