Hello everyone need a little advice on installing a new stereo and speakers in my 87 gn that has the concert sound 2 option dash speakers door speakers and rear deck. I want to install new head unit it does have power antenna. One of my questions is the concert sound I want to use all the speaker Openeings and want to know if someone sells a harness that is a plug and play for a after market unit. What is the best options for a new head unit single din or din and a half or will a new style double din work thanks for all your help in advance.