I had put this page up a few years ago... couldn't remember where it was, but amazingly I found it immediately on google...

http://www.fieldlines.com/matt/gauges.html

Pay no mind to the mis-information about the difference in redlines...I later found out that was because my GT set is for a 164... And as you can see, the phenolic board on the back of my rallye set is far worse from yours :-)

Sounds like you've got more the GT set rather than the "rallye" cluster... but that don't really matter... In your case, I'd guess that the connections at the crack are probably OK... but if they are disturbed, I bet you could scrape off some of the green stuff and solder in a jumper wire.

I had a video game controller once that *somehow* got broke in half... (I had a bad game). I managed to solder about 10 jumper wires on the PC board and duct tape it together... worked fine.

Putting that cluster in is easy though... all the connections are itentical to what you already have back there... Only bit of wiring I don't know about is the tach...

Good luck with it!
-Matt