Guages

I have a 73 240z 4spd, and my Speedo recently went out. I was driving to school in the morning and all of a sudden it jumped around, then just went to 0mph. The cable that goes to the transmission is fastened tightly, there are no bad bends, but it does have alot of fluid on it. Also my tach does not work, it is a 3 prong. Where should i begin to troubleshoot it at? And my temp. guage recently stoped working, it just sits all the way to the left. It was working great and i do not know what is worng.