  Since the launch of the Large Area Telescope (LAT) on board the Fermi
spacecraft in June 2008, the number of observed gamma-ray pulsars has increased
dramatically. A large number of these are also observed at radio frequencies.
Constraints on the viewing geometries of 5 of 6 gamma-ray pulsars exhibiting
single-peaked gamma-ray profiles were derived using high-quality radio
polarization data (Weltevrede et al., 2010). We obtain independent constraints
on the viewing geometries of 6 by using a geometric emission code to model the
Fermi LAT and radio light curves (LCs). We find fits for the magnetic
inclination and observer angles by searching the solution space by eye. Our
results are generally consistent with those previously obtained (Weltevrede et
al., 2010), although we do find small differences in some cases. We will
indicate how the gamma-ray and radio pulse shapes as well as their relative
phase lags lead to constraints in the solution space. Values for the flux
correction factor corresponding to the fits are also derived (with errors).
