  HST WFPC1 observations revealed 738 bright star clusters spread over the
inner 12 kpc of the interacting galaxy pair NGC 4038/39. If the young star
clusters (YSCs) formed in the global starburst are (proto-) globular or open
clusters has far-reaching consequences for the formation of elliptical
galaxies. Effective radii of the YSCs are difficult to measure on WFPC1 images,
their present luminosity function (LF) looks exponential. Evolutionary
synthesis models for star clusters of various metallicities are used to
individually age-date these clusters and describe their future luminosity and
color evolution. We identify a small but plausible number of old globular
clusters (GCs). Properly accounting for age spread effects significantly
changes the shape of the YSC LF from an exponential towards a Gaussian during
further evolution. This suggests that -- at least a major part of -- the YSCs
may well be GCs, implying that during a spiral-spiral merger+starburst the
specific GC frequency can increase significantly. Being preferentially observed
around those galactocentric radii where they formed, the YSCs serve as tracers
for the dynamical evolution of the global starburst in NGC 4038/39. We
tentatively report several radial trends in the YSCs' properties to be verified
by WFPC2 reobservations.
