Okay here is the 1% i know about a VSS in a 90 civic. The stock gauge cluster, speedo, is cable. The JDM cluster, speedo, is electronic (plugs in). So from my understanding you need to take the VSS off and use your speedo housing that was on your tranny or whatever cable tranny to make things work properly with cable.
If I'm wrong...please educate me. thanx.
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if you can only race me in a straight line then whats the point 
...91 SMF SCCA
http://www.flickr.com/photos/8341770@N07/5601083432/http://www.flickr.com/photos/8341770@N07/5601083432/ by http://www.flickr.com/people/8341770@N07/, on Flickr
I see people out there spending money on the car to improve it … If you spend half that effort just working on your driving skills, making you and the car work together as a team, then you’ll go faster – period. To make the car go a second faster on the track takes a lot more energy and money than making yourself drive it one second faster.
– the late Tom Thrash SCCA Solo E Production