The old-school Pilot 78g came in 4 nib sizes ... F, M, B, and BB. B and BB were both stub/italic nibs.
The Metropolitan was essentially the "same" pen but with a different body (79g plastic, Metro metal) and with the Metro having a "step down" where the pen parts joined ...
... that wasn't there on the 78g.
These were the 78g nibs:
My suspicion is that the Metro used the same set of nib sizes, including B and BB. (Typically, most pens available were F or M ... B and BB were harder to find. IIRC when the Metro first came out, it seemed like only the M was available.)
A few years back, the 78g seemed to be discontinued. A few years after that, they brought out a new-and-improved "78g+" pen.
I've never tried the 78g+, so can't say if the B nib is still a stub, or if they have a BB.
Hmmm, negative reviews? Maybe I was fortunate enough to get ahold of a good one, I could use it as a daily writer. My Leonardo Officina Momento 1.5mm is only used for special occasions as it is too broad with the 1.5mm stub.