  We present high-statistics results for neutral $B$-meson mixing and
heavy-light-meson leptonic decays in the quenched approximation from
tadpole-improved clover actions at $\beta = 6.0$ and $\beta = 6.2$. We consider
quantities such as $B_{B_{d(s)}}$, $f_{D_{d(s)}}$, $f_{B_{d(s)}}$ and the full
$\Delta B=2$ matrix elements as well as the corresponding SU(3)-breaking
ratios. These quantities are important for determining the CKM matrix element
$|V_{td}|$.
