I would like to know if the smoke dischargers on the M-901 where on the front part of the vehicle only or where they in other places? Also, would it be safe to say that not all M-901's had those smoke dichargers on them?

AFAIK the smoke grenade launchers were in the same location as for other M113-based variants (on the front slope).

Most of the M901 pics I've seen showed them in place (those which didn't were scale models pics )

Frenchy

The smoke grenade launchers on the M901, at least according to the manuals, were only to be fitted to the front of the vehicle, as on other M113 subvariants. They could be were capable of being removed, so you might see vehicles in various situations without them.