In this work we propose a preliminary seismic investigation of $delta$ Scuti stars in the Pleiades cluster, focusing on potential diagnostics of convection and core-overshooting. Taking into account the effect of fast rotation in the modelling, we compare observed frequencies for 4 $delta$ Scuti stars with radial linear instability predictions. A satisfying agreement is reached between the predicted ranges of unstable modes and those derived from observations for ``low-mass'' stars ($sim 1.55 M_{odot}$). However, a strong disagreement is found for ``high-mass'' stars ($sim 1.77 M_{odot}$), whatever the mixing length $(alpha)$ value. These results are compared with previous ones obtained for Praesepe.