Hello, I been combing the forums for some help on installing a new radio unit in my 1995 E320, but still have questions. The original Becker unit I’m replacing has 2 “harness” connections and a “tab” connection at the bottom rear that pops off when I pull out the unit. I purchased a wiring adaptor (Metra 70-1784) and the antenna adaptor (Metra 40-VW12). I have diagrams for the wire connections, but am trying to figure out a few things. #1- What does the original small 5x2 connection do and do I need it for my new stereo? #2- My new unit has 2 pre-out connections which I’m guessing would connect to an amplifier. Do I need a different wiring adaptor (Metra 70-1786) or need to connect to these Pre-outs at all? #3- Do I need to use the ground strap “tab” connection on my new unit? Thanks in advance for any help ya’ll give me!