  The $M/L$ ratios and absorption line-strengths of distant cluster galaxies
can be used to directly study their stellar populations, determine their
redshift of formation, their scatter in ages, and any dependence of their ages
on such internal properties such as velocity dispersion or mass. Comparing the
zero-point the fundamental plane in the $z=0.33$ cluster CL1358+62 to that in
Coma, we conclude that the redshift of formation for the stars in massive
cluster E/S0s was $z\ga 2$. The fundamental plane in CL1358+62 has the
following form: $r_e \propto \sigma^{1.31\pm 0.13}< I>_e^{-0.86\pm 0.10}$,
indicating that the last epoch of star-formation has very little dependence on
galaxy mass. The scatter in the CL1358+62 fundamental plane is also very low,
equivalent to a scatter in ages of $\sim 15%$.We have also analyzed the $M/L_V$
ratios of galaxies of type S0/a and later. These early-type spirals follow a
different plane from the E and S0 galaxies, with a scatter that is twice as
large as the scatter for the E/S0s. These residuals also correlate with the
residuals from the color-magnitude relation. Preliminary analysis of the
absorption line-strengths of the CL1358+62 early-types indicate that they are
well-described by uniformly old, single-burst stellar populations with
metallicity varying as a function of velocity dispersion.
