Well Fifi was eventually fixed up & MOTed on Christmas eve after spending about £600, happiest man alive. Now I have a question for you folks but first a little backstory.

I joined a model railway club recently & the chairman of the club gave me a few pieces. Two VV carbs (one with auto-choke, the other completely unused) & two P21 radios (one dated Jan '88, the other August '-2, the former digit rubbed off). I would like to use one of the radios in Fifi to give her a stock look inside but I have problems.

1: Are they mono or stereo?
2: how do you install them? The internet doesn't seem to know & the Haynes manual is hopeless
3: Can I do some jiggery-pokery inside to give them MP3 connectivity? Seen it done on a Cortina Resto on Youtube & I'd like to listen to my own music & not risk leaving Fifi with the aerial up for some oik to snap.

Answers would be very much appreciated