We report site-selective studies of the Zeeman splittings that are observed for magnetic fields up to 6.6T for different Eu incorporation sites in GaN. Utilizing resonant excitation with visible light, we are able to distinguish the site and find for one center (Eu1) a splitting into five components as expected for C3v symmetry. The corresponding g-values are 1.66 and 1.90. The two lines of another center Eu2 each split into two levels corresponding to g-values of 1.9 and 2.84. Most surprisingly a third center, for which only one line is clearly identified, a g-value of 6.16 is found which is larger than can be explained for a 7F2 purely ionic Eu state.