Is there a way to just add the maverick helicopter?
I tried by manually adding the necessary files and as well tried the automatic installation and then deleting the unneeded files afterwards. None of both approaches worked out, GTAIII stopps loading a new or a save game by about 80% of the progress bar.
That is how my default.ide looks, since I already used slot 151, 152, 154, 156 and 157 for addon cars. So I tried adding the maverick in the unused slots (154, 155, 158), but without success.