I bought my 1998 convertible GT last year. The Mach 460 was replaced with a Sony CDX GT640UI. Since then sound only came from tweeters. Thought the main speakers were bad. Bought new ones and still no sound. So I decided to take a look behind stereo. Oh crap! What a freaking mess! Whoever installed the unit did a real hack job. My question is, what exact harness do I need to make this right?