  The intermediate-age Magellanic Cloud clusters NGC 1978 and NGC 419 are each
found to contain substantial numbers of pulsating AGB stars, both oxygen-rich
and carbon-rich. Each cluster also contains two pulsating asymptotic giant
branch (AGB) stars which are infrared sources with a large mass loss rate.
Pulsation masses have been derived for the AGB variables, from the lowest
luminosity O-rich variables to the most evolved infrared sources. It is found
that the stars in NGC 1978 have a mass of 1.55Msun early on the AGB while the
NGC 419 stars have a mass of 1.87Msun early on the AGB. These masses are in
good agreement with those expected from the cluster ages determined by
main-sequence turnoff fitting. Nonlinear pulsation models fitted to the highly
evolved AGB stars show that a substantial amount of mass loss has occurred
during the AGB evolution of these stars. An examination of the observed mass
loss on the AGB, and the AGB tip luminosities, shows that in both clusters the
mass loss rates computed from the formula of Vassiliadis & Wood (1993)
reproduce the observations reasonably well. The mass loss rates computed from
the formula of Blocker (1995) terminate the AGB in both clusters at a
luminosity which is much too low.
