You can do some further detail checking on the site re. the topics of speedo, tach and clock for details. But the clock can be removed by first removing the glove box interior. The clock is held in place by a u-shaped 'keeper' with a knurled nut at the center of the back of the clock. Undo this, detach the electrical connector and the clock comes right out. There are a number of posts with options for repairing (redo the existing, or replace the innards with a quartz movement).
For the speedo, this is a stepwise ordeal. First you need to take out the tach, which involoves removing the underneath dash cover and some trim pieces, the tach has a keeper as well. Undo the knurled knob and the tach cable and the tach will pop right out. Change the light bulbs in the tach while you have it out.
The next in line is the center cluster. This car has a mechanical water temperature gauge that is directly connected to the block with a sensing bulb, so be very careful not to knick this. The oil pressure gauge is also mechanical, but is connected via a thin tube. Here is where you need to check the posts on the site, as I have heard that some have taken this out without having to disconnect the oil pressure line.
If you can the speedo is next in line, and is held in place with a keeper as well. Undo this and pop the thing out. Remember the tach keeper and the speedo keeper are DIFFERENT. The tach keeper has a small bump out (and should be insulated with rubber or tape) to ensure that there is no contact with the electricals.
The ground wire (brown) for the dash lights is also connected to the small knurled knob that holds the keeper (and instrument) in place for both the tach and speedo.
If you have some other dash work to do, taking the drivers seat out, which is held in place with four bolts will make the job much easier. Small hands also help as there are tight quarters behind the dash.
There should be a grey rubber gasket around the tach, speedo and center cluster. If this is old and cracked this would be a good time to replace them as well. They are available from most of the 113 vendors.
Jonny B
1967 250SL Auto