Answered my own questions;
Cummins replied that they had no record of this model. Full marks to them however, my request got passed around internationally. John Guslander, a Cummins service engineer dug up not only a manual, but the actual build sheet for this very generator. Apparently those made 1977 and prior had extra windings for use as a starter motor! If anyone is interested, PM me, I will be happy to forward the manual on this apparently rare Stamford D8C transformer controlled generator.
Cheers,
Hugh