Let ( M, F) be a Finsler manifold. We construct a 1-cocycle on Diff( M) with values in the space of differential operators acting on sections of some bundles, by means of the Finsler fonction F. As an operator, it has several expressions: in terms of the Chern, Berwald, Cartan or Hashiguchi connection, although its cohomology class does not depend on them. This cocycle is closely related to the conformal Schwarzian derivatives introduced in our previous work. The second main result of this paper is to discuss some properties of the conformally invariant quantization map by means of a Sazaki (type) metric on the slit bundle T Minduced by F.