I think that you are all making this sound WAY more complicated than it is. There are a few connections on a Becker pinstripe radio.
1. Antenna - that one is obvious
2. Power - there will typically be a BLACK wire coming out of the back of the radio. Connect that to 12V+
3. Ground - there is not typically a separate ground wire, but if there is, it will be BROWN
4. Speaker(s) - there are early style and later style plugs. The early style is a set of two prongs, about 1/2 inch apart. The later style is a little knob with two little flat prongs perpendicular to each other. If your radio takes the early style, it will either have one place to plug in a speaker, or it will have a strange 4-hole setup that let's you plug in one or two speakers depending on your desire:
A B
O O
O O
C D
If you want one speaker, you plug it into AB. If you want two speakers, you plug one into AC and one into BD. The size of the becker plug will not fit into CD or BC of AB. Note: the early plugs and this setup only applies to MONO radios.
If your radio has a separate amplifier, there will be a big grey cable from the radio plugged into the amplifier. The cable will include a ground wire that connects to the amplifier right next to the black plug. If your radio has a separate amplifier, the speaker plugs are on the amplifier, not the radio.
Your becker radio will probably have one or two recessed spade tip connectors. Those are switched 12V+. When you turn the radio on, those connectors become 12V+. These are used to signal a power antenna or to power an accessory such as the Becker cassette player.
Your becker will probably have a strange DIN plug exposed - I can't tell you about that except that don't mess with it.
Your becker will probably have another strange DIN plug with a black plastic cap on it. That is where you plug in the optional cassette player or the iPod adapter that you buy on ebay. NOTE: you must have something plugged into that plug, either the cap or an appropriate accessory or no sound will get to the amplifier and you will hear nothing.
The becker kickpanel speakers are available (I think) from Becker Autosound. You will also find them on ebay. I also have them and need to get some on ebay. They sound pretty good. These old Becker radios sound like crap with modern speakers that are expecting higher power. They sound really nice with the speakers to which they are matched.
Oh, and as previously mentioned, there are small-face beckers and big-face beckers. The dash opening changed in 1967 so you fortunately can install any large-face Becker. My least favorite would be Mexico because you get no presets, you will never use the cassette player, and I think you only get mono input if you try to connect an MP3 even if your Mexico is stereo. My favorite would be a Europa Stereo (because it is stereo) or a plain old Europa (because it is easy to get and nice).
I tend to think the radios with separate amplifiers sound a little better, but that might just be my imagination.
You do not need to pay $1000 for a good becker radio. You should be able to get a good Europa for $250 or less if you are patient. So decide if you want stereo or mono, and decide if you want an MP3 input. Then get back to us!
cheers
Scott