stereo wiring terminals

I just bought a 2007 340 Sundancer with the clarion cmd4a. It's located with the Ac and dc control panels in the salon. I want to access the wiring at back of the unit. I look at the install manual and it shows how you remove the screws mounting the unit...I did that and the unit pulls out of...

Where to buy wire terminals for stereo wiring harness block I'm adding front speakers to my 2007 185 Sport and would like to run the new speaker wires into the plastic wiring harness block that has all of the other stereo wires. The block can be opened with a grey push out but I have no idea...