Please post any upgrades or modifications you have done to your GC, which you think other GC owners would be interested in doing.
I will start with 2 I have done.
The first is the addition of a glow plug light for early models that do not have one.
When you energize the glow plugs, the metal strip, (bus bar), that runs between them has +12 Volts dc on it. If you get a 12 volt light, ground one end, and hook the other to the bus bar, you have a glow plug light.
Ideally, you use an instrument lamp that has the right socket to lock in one of the unused holes in the dash. You can get these where they sell aftermarket gauges. Or, even just buy a cheap gauge that comes with one, if they don't sell them separately.
There are also lots of bright led's now you could use. Keep in mind, unlike a light bulb, they do have polarities you need to observe.
If you cannot find a bulb that has the socket to fit securely in one of the empty holes in the dash, use aluminum foil tape to hold the lamp in the hole from the underside. You won't know the difference.
The lamp is not on long enough to get particularly hot, so there is not much need to worry about how well you connect it to the dash.