Yes, they are direct replacements for 120Y's & Sunny's. I used to grab the connection from the donor car & just splice that into the standard wiring. As for listening to CD's/Ipod's, I'd just find a part of the radio that didn't have a radio station braodcasting on it & tune the dial to that. It was a bit hard in a large city with lots of stations, but driving in the country there was always an empty spot. I would put a female 3.5 mm connection on the end of the wire & use a patch cable from the CD Player to the radio. The strangest version of the radio was out of an LX Bluebird that had an external balance system, which was a 4-way fader with a stick out the front which I mounted in the centre console of my Sunny Van. I even put the CD player in the glove box while driving along, so it wouldn't fall off the front seat.
I also thought there had to be a way to 'turn off' the radio, as happened when a cassette was put in the external cassette player. Maybe the antenna was disconnected some how. Maybe the power was turned off to the receiver. If this could be figured out you could simply put an on/off switch that could stop the radio reception & allow you to start using the CD player.

Whats even better is that that 5 pin DIN socket, which is a conection for an external tape deck, allows you to play portable CD players or Ipods throught the car stereo. Just get a standard 3.5 mm stereo cable from a set of air phones or such, cut of the speaker buds then connect these wires to a 5 pin DIN connector & run the CD or Ipod output through the radio. It takes a bit of trial & error to get the wires in the right pins, & I still haven't been able to work out how to earth out the radio so it doesn't play, but I've done this conversion on 2 Sunny's & a Navara. This allowed me to listen to CD's etc, & not have to worry about somebody breaking into the car to steal the stereo. I'd mainly listen to the local radio driving around town or too & from work, but when going on long trips, or when you just wanted a change, you could play something you liked. These style radios came in N12 Pulsars, A10 Stanza's & the P910 Bluebirds.