Yeah some of them are rly damn hard to find, it took me 14h to find 150 in Financial and 150 in Waterford, some of them you cant hear thats why you have to check all crazy places, it is on place which you wont expect, so first what you do when u get into one zone you should check all crazy places, most dumbest places check first. Hopefully you will find it, and yeah Prentiss is damn hard, I had 149/150 and last 1 was in Prentiss, took me 2h to find it, had to check all Prentiss zones.