Hi Russ,
Well .... the gearbox work is nothing to do with me, I had it refurbed at Mackie Transmissions in Glasgow (ZF agents) who were kind enough to take the photos for me while doing the work :-) I think the slab of beer I used as a bribe helped considerably! Retrofits, Audio etc is about my limitation.
The audio was somewhat time consuming but worth the effort. Interestingly, the holes in the rear shelf are factory. Mine didn't have premium sound but the holes are there so the JL Audio 6W3v3-4 (x2) subs fit with a little trimming of the rubber surrounds on them where they meet in the middle and obviously new holes for the mounting screws.
As I have the touchscreen, I wasn't about to strip it out and fit the non touchscreen climate panel and a 2 DIN unit. I have also fitted an ACM so the DAB unit and my IPOD connect via this.
So originally, my S had the basic sound with touchscreen but ALL the wiring was there ready and waiting for the premium sound along with the 2 holes in the rear shelf. I retrofitted a premium amp then took the speaker output from the premium amp and fed into an Audiocontrol LC8i which is a line output converter on steroids. In simple terms it is an eight channel, high-performance, line-output converter that accepts two, four, six or eight channels of speaker-level signal from a factory-installed amplifier (the Jaguar premium amp in my setup) or source unit and convert it to a high-quality, low-noise pre-amp signal which I feed into a JL Audio XD7005v2 700W 5-Channel Amplifier with JL Audio C3-650 front speakers, JBL coax rear speakers and JL Audio 6W3v3-4 (x2) subs. The LC8i also allows you to sum the signals from the inputs of Channels 2, 3, and/or 4. In other words, it allowed me to take the crossed over signal from the 8 front speaker outputs from the premium amp (into channels 1 & 2) and convert them into one high quality phono pre-amp signal which goes into the JL Audio amp. From there they go into the JL Audio crossovers for the C3-650 front speakers. Channel 3 is used to convert the rear speaker output from the premium amp into another high quality phono output for the JL Audio amp that feed the JBL coax speakers in the rear doors. Channel 4 is used for the two JL Audio subs in the same way.
As your car is pre the 2002.5 facelift, the setup is different for premium sound and sub location etc but anything is possible and achievable :-) I'm afraid all my knowledge is on my 2003 S
Hope that helps in some way and let me know if you need more info ... cheers ..... Jon