So, I am resurrecting this thread, as I finally got around to pulling the tachometer. As is so often the case, I stumbled into some blind alleys and it took many hours the first time, but I bet I could remove and refit in under 30 minutes at this point (fine, maybe an hour). Here's the right way to get this out if you, too have an early TC or SC with this tachometer setup (consider yourself lucky if you do, it's so very much more attractive and suited to the cabin's design, IMHO)
Basically, the top of the dashboard has to come off (I'd say fascia, but this was only fitted to export cars, so it's a dashboard! PHLLLLBBBBTTTT!!!) To make this happen, you have to:
1.) Remove the plastic cover for the warning lights by pushing up on the retaining clips (mine only had one for some reason) and pivoting it forward. If the dash top is in the way, preventing you from tilting the right side (LHD) or left side (RHD) forward, you can lift the bottom on both sides and pull it out that way.
2.) Remove the two screws holding the instrument panel in place.
3.) Remove the speedometer cable (open the glove box and reach under the speedometer. Towards the back, the cable end pokes though a hole at an angle to the back of the speedometer.
4.) Remove the rubber mat that sits on top of the shelf below the speedometer. I don't know about the later style, but this car had a mat that was cut to fit a car with no tachometer, so it slides under the tachometer binnacle and essentially wedges it into place.
5.) Remove the "A" pillar trim by unscrewing two screws on each side. It pulls backwards and out.
6.) Remove two screws, one from either end of the dash top. These were previously covered by the pillar trim, and are at the base of the pillars.
7.) Pull the speedometer forward. The material underneath it is sponge-like (or was at one time...) and you may need to push it down to get it under the lip of the dashboard. You don't need to disconnect any wiring or remove the instrument completely, just pull it forward and to the left (LHD) or right (RHD) as far as it wants to go.
8.) The tachometer binnacle should now be loose, and can be slid to the left (LHD) or right (RHD) enough to access the 5/16" nuts that secure the clock in the center of the dash. Remove them, along with their flat and spring washers.
9.) Remove the remaining two 5/16" nuts that hold the dash top in place. One is behind the instrument panel, and the other is directly in front of the passenger's seat. You can just look up and see it.
10.) Slide the dashboard toward you, and then wiggle it out, being careful not to harm the foam.
11.) Note that there are four tabs that the dash top slides onto when you put in back into place.
The tachometer is now free to remove, my experience was that there was nothing holding the binnacle in place, other than the top of the dashboard and the upward pressure from the rubber mat underneath it. Refitting is the reverse of removal - don't over-tighten the nuts when you put them back in!
Hopefully, that will prove helpful to someone else in the future.
Tom
PS: Super-annoying that the photos display at such a gigantic size, but I'd rather not resize all of them downwards. Does anyone have a good way to force the forum to show them at a smaller size?