  We convert the second class Proca model into a first class theory by using
the generalised prescription of Batalin, Fradkin and Tyutin. We then show how a
basic set of gauge invariant fields in the embedded model can be identified
with the fundamental fields in the proca model as well as with the observables
in the St\"uckelberg model or in the model involving the interaction of an
abelian 2-form field with the Maxwell field. The connection of these models
with the massive Kalb-Ramond model is also elucidated within a path integral
approach.
