I need help. I have a 92 RS with the 700. My problem is that my vehicle speed sensor is bad. I went with a new one from a cheap parts store and when I put it in, it wouldn't read anything (speedo). So I put the old one back in and it works as advertised. What should I do about this? Should I go with the one from GM or Try to get the 3rd sensor from the same people and work from there? I'm lost and would reaaly like to have a speedo that doesn't jump all over the place after it gets warmed up. Thanks in advance for any help you can give.