  We discuss theoretical AGB predictions for hydrogen-deficient PG 1159 stars
and Sakurai's object, which show peculiar enhancements in He, C and O, and how
these enhancements may be understood in the framework of a very late thermal
pulse nucleosynthetic event. We then discuss the nucleosynthesis origin of rare
subclasses of presolar grains extracted from carbonaceous meteorites, the SiC
AB grains showing low 12C/13C in the range 2 to 10 and the very few
high-density graphite grains with 12C/13C around 10.
