external url without port - nginx should listen to another port than default (80/443)

Hey there, atm I have following system: debian wheezy apache2 on port 80/443 nginx on port 8080 / 4443 (not gitlab instance)

I want to use gitlab on localhost:9292 with a reverse proxy on git.example.com (port 80) through apache2 to localhost:9292. Atm I have following configuration:

external_url 'http://git.example.com:9292'
nginx['listen_address'] = 'localhost'
nginx['listen_port'] = 9292

But what I need is something like that:

external_url 'http://git.example.com'
nginx['listen_address'] = 'localhost'
nginx['listen_port'] = 9292

Here the bug is, that nginx than is also using port 80 (because in external_url no port is defined), but nginx must only use port 9292. Otherwise I cannot start apache2, because there's a port conflict with the tho services.

Best regards, Ninos